Related Subjects:
|PTH Physiology
|Calcium Physiology
|Magnesium Physiology
|Calcitonin
|Hypocalcaemia
|Hypercalcaemia
|Hypomagnesaemia
|Hypermagnesaemia
|Primary Hyperparathyroidism
|Familial hypocalciuric hypercalcaemia (FHH)
|Sarcoidosis
⚠️ Post-op monitoring is vital: watch for hypocalcemia after surgery to ensure calcium levels return safely to normal. “Hungry bone syndrome” can occur after parathyroidectomy.
💊 About
- 🔹 Defined as albumin-adjusted serum calcium >2.6 mmol/L (UK standard).
- 📌 A common cause of mild, asymptomatic hypercalcemia.
- 🧬 ~10% associated with MEN I and MEN II.
- 👩 Predominantly affects females (prevalence ≈ 1 in 300).
⚙️ Physiology
- Most individuals have 4 parathyroid glands posterior to the thyroid.
- Secrete PTH in response to low calcium → increases renal calcium reabsorption, vitamin D activation, and bone resorption.
- PTH enhances active vitamin D (calcitriol) synthesis → ↑ gut absorption of calcium.
🧾 Aetiology
- 🌟 Single adenoma: 85% of cases.
- 🧬 Multiple adenomas: more common in MEN1.
- 🔄 Diffuse hyperplasia: all glands enlarged.
- ⚠️ Parathyroid carcinoma: <1% of cases.
🩺 Clinical Effects of Chronic Hypercalcemia
- May be asymptomatic for years (“stones, bones, groans, psychiatric overtones”).
- 🦴 Bone: pain, weakness, osteoporosis, fragility fractures.
- 🪨 Kidneys: renal stones, polyuria, nephrogenic DI, RTA.
- 🧠 Mental health: depression, cognitive changes, mood swings.
- 🍽️ GI: constipation, pancreatitis, peptic ulcer disease.
- ❤️ Cardiac: hypertension, arrhythmias.
🔍 Differential Diagnosis
- ⚠️ Malignant hypercalcemia: high PTHrP, high/normal urine calcium; exclude myeloma.
- 👪 Familial hypocalciuric hypercalcemia (FHH): AD, low urine calcium, normal/high PTH.
- 💊 Drug-induced: thiazides, lithium → raise calcium.
🧪 Investigations
- 🩸 Bloods: ↑ calcium, ↓/N phosphate, ±↑ ALP.
- 📈 PTH: inappropriately normal or raised in hypercalcemia.
- 🦴 X-rays: osteitis fibrosa cystica, subperiosteal bone resorption.
- 🚽 Urinary calcium: ↑ in ~30% cases.
- 📊 DEXA scan: assess bone density.
- 🖥️ Localization: neck ultrasound, sestamibi scan, venous sampling.
🩹 Management
- 💧 Conservative: hydration, stop calcium-raising drugs, regular monitoring.
- 🔪 Surgery (parathyroidectomy): for symptomatic or complicated cases.
– Remove 3½ glands in diffuse hyperplasia.
– Monitor closely for post-op hypocalcemia.
- 💊 Non-surgical candidates: monitor calcium, PTH, bone density 1–2 yearly; bisphosphonates or cinacalcet may help.
📌 Surgical Indications
- Ca²⁺ >0.25 mmol/L above normal.
- Urinary calcium excretion >10 mmol/24 hr.
- Creatinine clearance ↓ >30% from normal.
- Bone density T-score < -2.5.
- Patient request due to symptoms/lifestyle impact.
⚠️ Postoperative Complications
- ⬇️ Hypocalcemia (“Hungry bone syndrome”): treat with calcium ± vitamin D.
- 🗣️ Recurrent laryngeal nerve injury: hoarseness, voice change.
- 🩸 Bleeding/hematoma: rare but airway-threatening.
📚 References
