Osteoporosis

Meet the patient

A 72-year-old woman is admitted after slipping on a wet bathroom mat and landing on her hip — she cannot weight-bear, and the X-ray shows an intertrochanteric fracture. She had a wrist fracture at 64 that was "just plastered", takes no bone medication, and has lost five centimetres of height over the last decade. Her bloods come back normal: calcium 2.38, phosphate 1.1, ALP 95.^[1][5]

The single question that must be answered before she leaves hospital is the question that defines this whole disease: has anyone ever measured her bone, and is she on a bisphosphonate yet? The wrist fracture eight years ago was her first warning, missed. Everything below exists to make sure the second fracture never happens — and the single zoledronate infusion given within 90 days of this hip repair is the intervention that will cut her mortality by 28 percent.^[1][5]

What osteoporosis actually is — porous bone, the T-score, and the fracture that trumps the number

Osteoporosis is the most common metabolic bone disease, and its entire clinical importance is its fractures — the bone itself is painless until it breaks. It is a progressive systemic skeletal disorder of low bone mass and microarchitectural deterioration that raises bone fragility and fracture risk; the fractures cluster at the hip, vertebrae and distal forearm, and they carry major morbidity, mortality and cost, especially in older adults. So management is preventive end to end: find high-risk bone early with DEXA and FRAX, treat it, and stop the next fracture before it starts.^[1]

The operational WHO threshold is the DEXA T-score — the number of standard deviations the patient's bone mineral density sits below the young-adult healthy mean. Osteoporosis is a T-score of minus 2.5 or less at the femoral neck, total hip or lumbar spine; osteopenia is minus 1.0 to minus 2.5; normal is minus 1.0 or higher. Premenopausal women and men under 50 use the Z-score (age- and sex-matched) instead. The threshold examiners love to probe is the override clause: a low-trauma fracture of the hip or spine establishes osteoporosis regardless of the T-score — so a patient in the osteopenic band who has already fractured is treated as having the disease, not watched.^[1][2]

The consultant confession: I have seen too many patients told their DEXA was "only osteopenic, come back in two years" — having already fractured. The T-score is a probability tool, not a gatekeeper. The fracture is the disease.^[1]

The other defining feature is biochemical silence. In osteoporosis the serum calcium, phosphate and alkaline phosphatase are normal — and that one fact does more differential-diagnosis work than any scan. A raised calcium means malignancy or hyperparathyroidism; a raised ALP means osteomalacia, Paget or malignancy; a low calcium means osteomalacia or vitamin D deficiency. Normal across the board, plus a fragility fracture, is osteoporosis until proven otherwise.^[1]

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Two axes classify it, and only one is useful at the bedside. The historical pathophysiological split separates type 1 (postmenopausal) — oestrogen-driven, high-turnover, trabecular, vertebral and wrist fractures in women aged 50 to 70 — from type 2 (senile) — low-turnover, cortical and trabecular, hip and pelvic fractures in men and women over 70. The axis that actually changes management is primary versus secondary: roughly half of women and the majority of men with a fragility fracture have an identifiable secondary driver, so a structured hunt is mandatory in every new diagnosis.^[1]

^[1]

How common, who breaks, and where to cast the net

Osteoporosis is silent, common, and astonishingly asymmetric across sex. An estimated 200 million people live with it worldwide — an osteoporotic fracture happens roughly every 3 seconds — and the lifetime risk after 50 is about one in three women and one in five men. Hip-fracture incidence climbs exponentially in women after 50 and in men after 70, and as populations age the global burden is projected to roughly double.^[1]

^[1]

The burden lands hardest on the hip. Of an estimated 9 million osteoporotic fractures a year, about 1.6 million are hip fractures, projected to rise sharply as Asia ages. Hip fracture consumes a major share of every developed health system's orthopaedic and rehabilitation budget, and the loss of independence afterwards is the single largest driver of new nursing-home admissions in older women. Women dominate the postmenopausal cohort, but men die more often after a hip fracture — partly because the diagnosis is never made and no bone therapy is ever started.^[1]

Risk factors split into fixed and modifiable or iatrogenic, and the modifiable list is the one an examiner wants verbatim. Fixed: age, female sex, menopause, parental history of hip fracture, low body mass index, and white or Asian ethnicity. The actionable, secondary drivers are the list to reel off: oral glucocorticoids, hypogonadism (premature menopause, anti-androgen therapy, hyperprolactinaemia), hyperthyroidism, primary hyperparathyroidism, chronic kidney disease, malabsorption (coeliac, post-gastrectomy, bariatric), chronic liver disease, rheumatoid arthritis, low calcium and vitamin D, immobility, and low BMI.^[1][2]

Why bone breaks — RANKL, OPG, and the oestrogen that holds the brake

Bone is not inert — it is continually remodelled, and osteoporosis is a remodelling imbalance where resorption outruns formation. Two cell lineages do the work in coupled basic multicellular units: osteoclasts (multinucleated, haematopoietic-derived) resorb old bone, and osteoblasts (mesenchymal-derived) lay down new osteoid that then mineralises. Over any cycle in osteoporosis, resorption exceeds formation, the net balance is negative, trabeculae thin and perforate, cortex becomes porous, and bone strength — which depends on density and quality (architecture, mineralisation, microdamage) — falls until a minor load snaps it.^[1]

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Etymology for viva gold: osteo is Greek for "bone", poros for "passage" or "pore" — osteoporosis is literally "porous bone". Drop that and the examiner knows you have read past the headline.^[1]

The molecular control of the balance is the RANK / RANKL / OPG axis, and it is the single most examinable pathway in bone. RANKL (receptor activator of nuclear factor kappa-B ligand), expressed by osteoblasts and stromal cells, binds RANK on the osteoclast precursor and drives its differentiation, activation and survival. The decoy receptor osteoprotegerin (OPG), also made by osteoblasts, mops up RANKL and blocks it, braking resorption. After the menopause, oestrogen deficiency removes the brake: RANKL and the pro-resorptive cytokines (IL-1, IL-6, TNF-alpha) rise while OPG falls, osteoclasts are recruited in droves, and resorption accelerates — producing high-turnover, type 1 (postmenopausal) osteoporosis with selective trabecular loss.^[1]

A remodelling cycle runs a fixed sequence — activation, resorption, reversal, formation, mineralisation, resting — normally ending in balanced repair. The conductor is the osteocyte, the most abundant and long-lived cell in bone, exquisitely mechanosensitive through its lacuno-canalicular network: load it and it promotes formation; unload it (immobility, paralysis, weightlessness) and it signals for resorption. The molecular link from sensing to building is Wnt signalling, which osteocytes restrain by secreting sclerostin (SOST) and Dickkopf-1. Ageing raises sclerostin, osteoblast formation declines, osteocytes senesce and die, and each cycle underfills its resorption cavity — the lesion of low-turnover, type 2 (senile) osteoporosis and the hip and pelvic fractures of advanced age.^[1]

The same final common pathway is amplified by every secondary driver. Glucocorticoids suppress osteoblast and osteocyte survival and raise resorption; hyperthyroidism and excess thyroid replacement accelerate turnover; hyperparathyroidism drives osteoclast-mediated resorption directly; hypogonadism removes the same oestrogen or testosterone brake as the menopause; immobility unloads the osteocyte. Knowing the axis is knowing the drugs: bisphosphonates and denosumab both blunt resorption, while teriparatide and romosozumab push the formation side.^[1]

^{[6] [20]}

The silent disease — how the patient actually looks

Osteoporosis produces no symptoms until bone breaks — and the break is almost always from a trivial fall. Many patients are flagged first by a DEXA done for risk factors; far too many are flagged only by the first fracture. The presentations cluster into three patterns, sometimes with the chronic deformity of accumulated vertebral collapse.^[1]

Vertebral (fragility) fractures are the commonest. About two-thirds are clinically silent and are found incidentally on chest or abdominal imaging; the rest present with acute or subacute mid- to lower-thoracic and upper-lumbar back pain after minimal or no trauma — often just bending, lifting or coughing — that is local and mechanical, eased by rest and worse sitting forward. Multiple wedge compressions shorten and angulate the spine: loss of height over 4 cm, a progressive thoracic kyphosis (the dowager's hump), a protuberant abdomen where the rib margin meets the pelvic brim, and in severe cases a restrictive ventilatory defect. A painful vertebral fracture is managed with stepped analgesia, early mobilisation, and — for persistent severe pain — percutaneous vertebroplasty or kyphoplasty.^[1]

Hip fractures present after a fall from standing height with groin pain, an externally rotated and shortened leg, and inability to weight-bear — a surgical emergency under a combined orthogeriatric model (see below). Distal forearm (Colles) fractures classically follow a fall onto an outstretched hand in a postmenopausal woman — the median age is younger than for hip fracture, and it is often the first hint that the skeleton is failing.^[1]

^[1]

The unifying clue across all of them is low-energy trauma — a fall from standing height or less, or a force that would not break a healthy bone. Any fracture sustained in such circumstances, at any age, establishes osteoporosis until proven otherwise and triggers the work-up below.^[1]

Split the mimics — the differential face-off

The decisive discriminator is almost always a biochemical or radiological abnormality that osteoporosis lacks. Because osteoporosis is biochemically silent and presents with fracture or low density, the differential is the set of conditions that also produce bone pain, fracture or low bone mass:^[1]

^[1]

The one-line discriminator beneath: in osteoporosis the serum calcium, phosphate and ALP are normal; raised calcium is malignancy or hyperparathyroidism; raised ALP is osteomalacia, Paget or malignancy; low calcium is osteomalacia or vitamin D deficiency. And always think myeloma in any older patient with a fragility fracture — check the full blood count, renal function, calcium, and serum and urine protein electrophoresis.^[1]

The bedside round — height, hips, and the secondary-cause hunt

Bedside assessment rarely makes the diagnosis; it confirms the fracture pattern, sizes up fall risk, and hunts the secondary driver. Three aims, in this order:^[1][2]

• Measure height every visit. Loss of more than 4 cm from the young-adult peak is a sensitive trigger to image the thoracolumbar spine for occult vertebral fractures.
• Weigh and calculate BMI. A BMI under 21 to 22 is an independent risk factor and a FRAX input.
• Examine for kyphosis (wall-to-occiput gap), proximal muscle weakness (a proximal myopathy whispers osteomalacia, not osteoporosis), and focal spinal tenderness (vertebral fracture — or, if constant and progressive, malignancy).
• Screen the secondary drivers at the bedside — thyrotoxicosis or hypothyroidism, Cushing syndrome (striae, bruising, central obesity, proximal myopathy), hypogonadism in men (loss of secondary sexual hair, small testes), and chronic liver or renal disease.^[1][2]

A prior fragility fracture is at once the strongest risk factor and a diagnostic event — examine for old fractures at the wrist, hip, spine, proximal humerus and pelvis, and corroborate with prior imaging. The patient who has already fractured is the one most likely to fracture again, which is why the highest-yield intervention in the field is finding her.^[1]

DEXA, FRAX and the secondary hunt — the fixed diagnostic ladder

Investigation answers four questions: how dense is the bone, what is the absolute fracture risk, is there an occult vertebral fracture, and is there a secondary cause? Run them as a set.^[2]

DEXA of the lumbar spine, total hip and femoral neck is the gold standard, reported as the T-score (standard deviations below the young-adult mean) in adults over 50 and the Z-score (age- and sex-matched) in premenopausal women and men under 50. The WHO thresholds, reproduced exactly: osteoporosis equals minus 2.5 or less; osteopenia equals minus 1.0 to minus 2.5; normal equals minus 1.0 or higher; severe (established) osteoporosis equals minus 2.5 or less plus a fragility fracture. DEXA is reported per-site because arthritis, aortic calcification or an existing vertebral fracture can artefactually raise the spine reading, so use the lowest of femoral neck, total hip and spine.^[1]

^[2]

FRAX turns the risk factors into a 10-year fracture probability. It integrates age, sex, BMI, prior fragility fracture, parental hip fracture, current smoking, glucocorticoid use, rheumatoid arthritis, secondary causes, and alcohol 3 or more units daily — with or without femoral-neck BMD — into the 10-year probability of hip fracture and of a major osteoporotic fracture (clinical spine, hip, forearm, proximal humerus). FRAX earns its keep in the osteopenic range, where it decides who to treat, and it is calibrated to national epidemiology. Remember its blind spot: it takes yes/no inputs and does not accumulate dose, so it underestimates risk in heavy smokers, high-dose steroids and the very-high-risk patient.^[10][2]

Vertebral fracture assessment (VFA) runs on the DEXA machine at the time of BMD, or as a lateral thoracolumbar spine X-ray, to catch the morphometric vertebral fractures that are clinically silent but, once present, establish the diagnosis and independently raise future fracture risk. Indications: height loss over 4 cm, historical height loss over 6 cm, recent non-traumatic back pain, and osteopenia with age over 70 in women or 80 in men.^[2]

Screen for a secondary cause in every new diagnosis — the panel that pays for itself: full blood count and ESR, serum calcium, phosphate, albumin and ALP, renal and liver function, TSH, 25-hydroxy vitamin D, and serum testosterone in men. Add when the picture demands it: intact PTH, 24-hour urinary calcium (hypercalciuria or malabsorption), serum and urine protein electrophoresis with serum free light chains (myeloma), coeliac serology (tissue transglutaminase IgA) in unexplained or low-BMI disease, a morning cortisol or overnight dexamethasone suppression (Cushing), gonadotrophins (FSH, LH) to characterise hypogonadism, and bone turnover markers (CTX, P1NP) as a baseline and adherence check. Bone biopsy is reserved for atypical presentation or suspected osteomalacia.^[1][2]

One caveat worth stating: plain X-rays confirm a fracture but do not measure density. Bone must lose roughly 30 to 40 percent of its mineral content before osteopenia is visible radiographically — so a normal-looking film never excludes osteoporosis. DEXA is required.^[1]

Acute fracture is a surgical event, not a medical one

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^[1]

There is no resuscitation for osteoporosis itself — but an acute fragility fracture is a time-critical surgical and orthogeriatric event, and the medical team's job is to start bone therapy before discharge.^[1][5]

Acute hip fracture is a surgical emergency managed best under a combined orthogeriatric model: prompt work-up, early surgery, early mobilisation, and prompt osteoporosis therapy before discharge. Delay is lethal: in a UK regional audit of over 5000 patients, surgical delay beyond 36 hours for logistical (non-medical) reasons increased one-year mortality by 20 percent — which is why national hip-fracture audits track time-to-theatre. The single intervention that changes outcome after repair is zoledronic acid 5 mg intravenously within 90 days of surgical repair, which cut further clinical fractures by 35 percent and all-cause mortality by 28 percent in the HORIZON recurrent-fracture trial. Acute painful vertebral fracture is managed with stepped analgesia, early mobilisation, brief external support, and vertebroplasty or kyphoplasty for persistent severe pain.^[5][23]

The stepwise drug ladder — lifestyle, bisphosphonate, then the heavy artillery

Definitive management is a stepwise ladder: universal lifestyle and supplements for everyone, a first-line bisphosphonate for most, then denosumab or an anabolic for severe disease, then a drug-holiday review.^[1][2]

Step 1 — the universal baseline. Exercise that challenges balance and strength prevents falls: the Cochrane synthesis of 108 randomised trials found exercise reduced the rate of falls by 23 percent in community-dwelling older people — so prescribe weight-bearing and resistance activity plus a structured fall-prevention programme (home-hazard reduction, balance training, vision correction, medication review, as distilled from the NICE falls guideline). Add smoking cessation and limit alcohol. Ensure adequate calcium (about 1000 to 1200 mg a day, diet first) and vitamin D, correcting deficiency before starting an antiresorptive — but calcium and vitamin D alone are adjuncts, not substitutes, for specific therapy in established disease.^{[1][2][21][22]}

Step 2 — first-line bisphosphonate. For osteoporosis, or osteopenia plus a FRAX over threshold, start a bisphosphonate: synthetic pyrophosphate analogues that bind hydroxyapatite and cripple osteoclast function and survival. In the Fracture Intervention Trial, alendronate cut new morphometric vertebral fractures by 47 percent (and hip fracture by 51 percent) in women with existing vertebral fractures; risedronate cut vertebral fractures by 41 percent over 3 years (VERT) and hip fracture by 30 percent in elderly women with confirmed osteoporosis (HIP); zoledronic acid 5 mg intravenously over at least 15 minutes once yearly is preferred when adherence or upper-gastrointestinal tolerability is the issue, in acute fracture, or for patients who prefer intermittent dosing. Counsel alendronate takers to take it fasting with water and stay upright for at least 30 minutes.^{[3][4][11][12][13]}

^{[3] [4] [11] [12] [13]}

Step 3 — denosumab and the anabolics. Denosumab 60 mg subcutaneously every 6 months reduced vertebral fracture by 68 percent, hip by 40 percent and nonvertebral by 20 percent over 3 years (FREEDOM) and suits patients who prefer twice-yearly dosing; it is not renally cleared, and hypocalcaemia risk rises as kidney function falls (eGFR under 15), so monitor calcium in advanced CKD — but it must never be stopped without a transition antiresorptive, because withdrawal causes a rebound in bone turnover above baseline and a cluster of multiple vertebral fractures within months. The anabolics — teriparatide (PTH 1-34) 20 micrograms subcutaneously daily (65 percent fewer new vertebral fractures vs placebo) and abaloparatide 80 micrograms daily (fewer new vertebral and nonvertebral fractures over 18 months in ACTIVE) — stimulate osteoblasts and build new bone; they are reserved for severe or very-high-risk disease, with treatment duration limited to about 2 years before an antiresorptive lock-in.^{[1][6][7][20][26][29]}

Step 4 — the older agents. Raloxifene 60 mg daily, a SERM, cut new vertebral fractures by about 30 to 50 percent in the MORE trial but did not significantly reduce nonvertebral fracture; it also reduced invasive (estrogen-receptor-positive) breast cancer, at the price of more venous thromboembolism (RUTH) and hot flushes. Hormone therapy reduces total and hip fractures (WHI: total fractures down 24 percent over 5.6 years), but because the global index showed no net benefit it is now reserved for menopausal symptom control in younger postmenopausal women at the lowest dose for the shortest time. Calcitonin is a weak antiresorptive; the PROOF trial's 200 IU intranasal dose reduced vertebral fracture by about one-third (RR 0.67) while other doses failed, so its main remaining use is short-term analgesia in acute painful vertebral fracture.^{[14][15][16][17]}

Step 5 — the drug holiday. After 3 to 5 years of an oral bisphosphonate (or 3 years of IV zoledronate), reassess. In a stable, lower-risk patient with a T-score above minus 2.5 and no recent fractures, a 2 to 3 year holiday exploits the drug's prolonged skeletal retention while trimming the rare risks of atypical femoral fracture and osteonecrosis of the jaw. In a high-risk patient (T-score below minus 2.5, prior hip or spine fracture, or fracturing on therapy) treatment continues — up to 10 years has a favourable benefit-to-risk profile. The holiday is monitored with DEXA and turnover markers, and therapy resumes if risk rises, density falls, or a fracture occurs. A drug holiday applies only to bisphosphonates — never to denosumab.^[1][2]

^{[2] [10] [18] [19]}

Glucocorticoids, men, and the build-then-lock patients

Glucocorticoid-induced osteoporosis (GIOP) is the commonest secondary osteoporosis and the most rapidly destructive — bone loss is fastest in the first months of therapy. The 2017 American College of Rheumatology guideline says every adult starting or continuing glucocorticoids for 3 months or more should have fracture risk assessed: adults at moderate-to-high risk get calcium and vitamin D plus an additional osteoporosis medication (oral bisphosphonate preferred), with reassessment every year while treatment continues. FRAX already takes glucocorticoid exposure as a dichotomous input but ignores dose, so adjust it: at high doses (over 7.5 mg prednisolone daily) fracture probabilities can be revised upward by about 15 percent, while low doses (under 2.5 mg) revise them down.^[18][19]

Male osteoporosis is under-recognised, and that under-recognition kills. About one in five men over 50 will fracture, and secondary causes turn up in roughly half to two-thirds of men with a fragility fracture — most often hypogonadism, steroid therapy (including for COPD and inflammatory disease), alcohol excess, smoking and hyperthyroidism. Always measure serum testosterone with LH and FSH in any man with low bone mass; testosterone replacement treats the hypogonadism and lifts BMD. Bisphosphonates and denosumab are first-line in men, teriparatide for severe disease.^[1]

Post-fracture secondary prevention lives in the Fracture Liaison Service (FLS). Every patient over 50 presenting with a fragility fracture is identified, investigated (DEXA, secondary-cause screen) and started on therapy. The Cochrane-style meta-analysis of 74 controlled studies found FLS care raised BMD testing by 24 percentage points, treatment initiation by 20, and adherence by 22 — and cut re-fracture risk and mortality versus usual care, which makes FLS coverage the single most effective intervention to close the treatment gap.^[1][24]

Very-high-risk patients get anabolic first, then a lock. Patients with multiple or recent fractures, a T-score below minus 3.0 or minus 3.5, or a fracture sustained while on antiresorptive therapy are candidates for an anabolic agent first (teriparatide, abaloparatide or romosozumab), followed by a potent antiresorptive to lock in the gain. This build-then-lock sequence delivers larger BMD gains and fewer fractures than starting with an antiresorptive in this group — which is why romosozumab exists.^[8][9]

Transplant and cancer-therapy bone loss is anticipatory. Patients about to start androgen-deprivation therapy for prostate cancer, aromatase-inhibitor therapy for breast cancer, or solid-organ or stem-cell transplantation face rapid, predictable bone loss within the first year. Measure a baseline DEXA, start calcium and vitamin D, and initiate a bisphosphonate (or denosumab) before or at the start of the gonadotropin-releasing-hormone agonist, aromatase inhibitor, or transplant immunosuppression — not after the bone is lost.^[1]

The traps that harm patients — read this twice

Most preventable osteoporosis harm is a timing error — treating too late, stopping the wrong drug, or forgetting that a fracture already is the diagnosis.^[1][2]

• Waiting for the T-score to cross minus 2.5 before treating a patient who has already fractured. A fragility fracture establishes the disease whatever the score; treating the next fracture, not the last, is the whole point — and FLS programmes that close this gap cut re-fracture risk and mortality.^[1][24]
• Stopping denosumab without a transition antiresorptive. Withdrawal triggers a rebound of bone turnover above baseline and multiple vertebral fractures can cluster within months; the ECTS position is to start alternative antiresorptive therapy about 6 months after the final denosumab injection.^[20]
• Forgetting prophylaxis on long-term glucocorticoids. Anyone starting or continuing glucocorticoids for 3 months or more earns a fracture-risk assessment; at moderate-to-high risk that means calcium and vitamin D plus an osteoporosis medication (oral bisphosphonate preferred), and high-dose steroid exposure revises FRAX probabilities upward about 15 percent.^[18][19]
• Misreading the biochemistry. A raised calcium or ALP in a "fragility fracture" patient is not osteoporosis — it is hyperparathyroidism, myeloma, osteomalacia or Paget disease, and the treatment is entirely different.
• Leaving a hip-fracture patient on no bone therapy at discharge. A single zoledronate infusion within 90 days of repair cuts mortality by 28 percent; omitting it is a measurable, preventable death.^[5]

^[20]

Complications, prognosis — and the 28 percent that decides a hip-fracture service

The disease's complications are the fractures themselves; the drug's complications are the rare ones you must name. Trial-proven therapy drops vertebral fracture by roughly 40 to 70 percent and hip fracture by 30 to 50 percent (FIT, VERT, HIP, HORIZON PFT, FREEDOM), and a single zoledronate infusion after a hip fracture cut new clinical fractures by 35 percent and all-cause mortality by 28 percent in the recurrent-fracture trial — the justification for prompt secondary prevention.^{[3][4][5][6][12][13]}

Hip fracture carries a one-year mortality of 20 to 30 percent, a catastrophic loss of independence (half of previously independent patients need help with activities of daily living afterwards), and a high rate of immobility complications — venous thromboembolism, pressure ulcers, pneumonia, urinary infection. Vertebral fractures cause acute and chronic back pain, kyphosis with reduced vital capacity and restrictive physiology, early satiety and weight loss from the reduced abdominal cavity, and a raised future fracture and mortality risk proportional to severity.^[1]

Drug complications are exactly what an examiner probes. Long-term bisphosphonates rarely cause atypical femoral fracture — a transverse, non-comminuted subtrochanteric or diaphyseal fracture, often preceded by weeks of prodromal thigh pain — and osteonecrosis of the jaw (exposed non-healing bone, usually after dental extraction in high-dose malignancy therapy). Both are rare in osteoporosis dosing but accumulate with duration, which is the rationale for the drug holiday. Acute-phase reaction (fever, myalgia, arthralgia) hits about 10 to 15 percent after the first IV zoledronate and is self-limiting; hypocalcaemia can follow zoledronate or denosumab, so replete vitamin D first.^[1][2]

Pregnancy, the frail elderly, CKD, and the diabetic paradox

Pregnancy and lactation cause a transient, reversible loss of 3 to 10 percent of bone mass; bisphosphonates are contraindicated (teratogenic, long skeletal half-life), so management is calcium, vitamin D and lifestyle, with the rare pregnancy- and lactation-associated osteoporosis referred to a specialist.^[1]

The elderly and frail are the highest-risk group and benefit most from fall-prevention programmes, vitamin D supplementation (which reduces falls in the deficient), home-hazard modification and IV zoledronate to overcome adherence problems — while avoiding sedating drugs and overtreatment that causes hypotension and falls.^[1]

Chronic kidney disease changes the playbook. Osteoporosis treatment is broadly similar up to CKD stage 3, but in stages 4 to 5 the evidence thins — KDIGO's framework stresses optimising mineral metabolism (phosphate, calcium, parathyroid hormone) before bone-targeted drugs, because adynamic bone disease can coexist with low bone mass and BMD alone cannot tell them apart. Denosumab is not renally cleared and is usable in advanced CKD, but its hypocalcaemia risk rises steeply as eGFR falls — population data show a substantially higher incidence of mild and severe hypocalcaemia below an eGFR of 15 mL per minute — so calcium and vitamin D are monitored closely.^{[25][26][27][28]}

The diabetic paradox is worth a viva mark. Patients with type 2 diabetes have higher than average bone mineral density yet a paradoxically higher fracture risk, because chronic hyperglycaemia, advanced glycation end-products and altered collagen cross-linking wreck bone quality rather than quantity. DEXA and FRAX both underestimate skeletal fragility in diabetes, so use a lower threshold to treat and watch fall risk. The trabecular bone score (TBS), derivable from DEXA, helps capture the hidden risk.^[1]

The trials that built the ladder

Modern osteoporosis therapy rests on a sequence of large placebo-controlled RCTs, each of which earned a drug its place on the ladder.^[3][4][6][7]

^{[3] [11] [4] [5] [6] [7] [8] [9]}

US, UK, and the rest — where the thresholds diverge

Regional guideline differences are examinable and reflect different health-system economics. The FRAX algorithm itself was built on UK epidemiology.^[10]

^{[2] [10] [1]}

Monitoring, and prevention across a lifetime

Monitoring combines DEXA, turnover markers and an adherence check — and the commonest cause of treatment failure is that the patient never took the drug. Repeat DEXA every 1 to 2 years in high risk and up to 3 years in stable disease, and look for the least significant change — a change exceeding roughly 3 to 5 percent at the spine and 3 to 6 percent at the hip to be real. A stable or rising T-score confirms response; a falling T-score or rising turnover markers on therapy signal non-adherence (by far the commonest cause), an unrecognised secondary cause, or treatment failure, and should trigger review. Serum CTX should fall by at least one-third within 3 to 6 months of an oral bisphosphonate, or within days of IV zoledronate; a failure to fall means the drug was not taken or not absorbed.^[2]

Prevention is staged across life. Build a high peak bone mass in youth (calcium, vitamin D, weight-bearing exercise; avoid smoking and excess alcohol); maintain bone through midlife; and detect and treat risk after the menopause and in older age. Population strategies — vitamin D and calcium sufficiency, physical activity, smoking and alcohol moderation, fall prevention, and Fracture Liaison Service coverage of every fragility-fracture patient — do more to reduce the fracture burden than any single drug.^[1]

The mantra, and the mnemonics

^{[1] [2] [20] [21]}

The mantra: A fragility fracture is osteoporosis whatever the score — bisphosphonate first, never stop denosumab without a transition.^[1][6]

Ward-round test — three stems, thirty seconds each

Stem 1 — the missed warning fracture (answer)ShowHide

A 72-year-old woman is admitted with an intertrochanteric hip fracture after a fall from standing height. She had a Colles fracture at 64 that was plastered and discharged; she takes no bone medication. Bloods: calcium 2.38, phosphate 1.1, ALP 95. Her DEXA femoral-neck T-score is minus 2.2. What is the diagnosis, and what must happen before she goes home? Model: She has established osteoporosis — the wrist fracture eight years ago already made the diagnosis regardless of the T-score, and the normal calcium, phosphate and ALP confirm it is osteoporosis, not osteomalacia, myeloma or hyperparathyroidism. Before discharge she must have early surgical repair under an orthogeriatric model (logistical delay past 36 hours raises one-year mortality by about 20 percent in UK audit data), a zoledronic acid 5 mg IV infusion within 90 days of repair (cuts further clinical fractures by 35 percent and all-cause mortality by 28 percent), a secondary-cause screen, calcium and vitamin D, and a bisphosphonate started — ideally via a Fracture Liaison Service. Waiting for the T-score to cross minus 2.5 is the preventable error that cost her this hip.^[5][23][24]

Stem 2 — the glucocorticoid trap (answer)ShowHide

A 58-year-old woman with rheumatoid arthritis has taken prednisolone 10 mg daily for 8 months. Her femoral-neck T-score is minus 1.8, she has never fractured, and her unadjusted FRAX 10-year hip-fracture probability is 1.8%. Does she warrant bone-protection therapy, and why? Model: Yes. Glucocorticoid exposure is itself a FRAX input, but FRAX ignores dose — and at prednisolone 10 mg daily (a high dose, over 7.5 mg) the guideline adjustment revises her fracture probabilities upward by about 15 percent, so the unadjusted 1.8 percent underestimates her true risk. More importantly, the American College of Rheumatology GIOP guideline says any adult on glucocorticoids for 3 months or more needs a fracture-risk assessment, and adults at moderate-to-high risk get calcium and vitamin D plus an osteoporosis medication (oral bisphosphonate preferred) — she is already 8 months in, in a disease whose bone loss is fastest at the start of therapy. Teriparatide is one of the options if her risk is very high or a bisphosphonate is unsuitable. Waiting for the T-score to cross minus 2.5 — or for a fracture — is the preventable error.^[18][19]

Stem 3 — the denosumab withdrawal trap (answer)ShowHide

A 68-year-old woman has been on denosumab 60 mg subcutaneously six-monthly for 4 years with a stable T-score of minus 2.6. Her GP stops it because she is tired of injections and prescribes calcium and vitamin D alone. Four months later she presents with severe back pain and imaging shows three new vertebral fractures. What happened, and what was the correct plan? Model: This is the denosumab rebound — stopping denosumab causes bone turnover to rise above pre-treatment baseline, and multiple vertebral fractures can cluster within months. Denosumab must never simply be stopped: the European Calcified Tissue Society advises starting alternative antiresorptive therapy about 6 months after the final denosumab injection (a bisphosphonate such as oral alendronate or IV zoledronate), with turnover markers helping to define the regimen — though even bridging only partially blunts the rebound, and BMD loss or fracture can still occur. A drug holiday applies only to bisphosphonates, never to denosumab. Because she is fracturing in the rebound window she now needs prompt specialist care and likely anabolic therapy (teriparatide or romosozumab) followed by a potent antiresorptive.^[20]

References29ShowHide

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