Hypoparathyroidism
Low parathyroid hormone causes persistent low blood calcium with high phosphate — leading to tingling, muscle cramps, seizures and cataracts if untreated. Most often from neck surgery; less commonly autoimmune or genetic.
What it is
Hypoparathyroidism is a deficiency of parathyroid hormone (PTH), the master regulator of blood calcium. Without enough PTH, intestinal calcium absorption falls, bone calcium release stops and kidneys excrete more calcium and reabsorb more phosphate. The result is chronic hypocalcaemia with hyperphosphataemia. The commonest cause is iatrogenic — accidental removal of or damage to parathyroid glands during thyroidectomy, parathyroidectomy or radical neck dissection. Other causes: autoimmune destruction (isolated or polyglandular autoimmune syndrome), genetic syndromes (DiGeorge, autosomal dominant hypocalcaemia), severe magnesium deficiency (suppresses PTH secretion), and rare infiltrative disease. Treatment combines oral calcium and active vitamin D (calcitriol), with hormone replacement (recombinant PTH) for refractory cases.
Key lab markers
- Calcium (total + ionised) — low; corrected for albumin or ionised preferred.
- PTH — inappropriately low or low-normal for the hypocalcaemia (the diagnostic feature).
- Phosphate — high (uninhibited renal reabsorption).
- Magnesium — must always be checked; severe low Mg² causes functional hypoparathyroidism.
- Vitamin D (25-OH and 1,25-OH) — low active form due to PTH-dependent kidney conversion.
- 24-hour urine calcium — used to titrate treatment (hypercalciuria limits how aggressively you can replace).
Symptoms
- Perioral and fingertip tingling (paraesthesia) — earliest classic
- Muscle cramps, hand spasms (Trousseau's sign), facial twitch (Chvostek's sign)
- Tetany; in severe cases laryngospasm or seizures
- Cataracts (chronic untreated)
- Calcification of basal ganglia → movement disorders, parkinsonism
- Brittle nails, dry skin
When to discuss with a doctor
New persistent perioral tingling, muscle cramps or hand spasms — particularly after recent neck surgery — must be evaluated promptly with calcium, magnesium and PTH. Acute symptomatic hypocalcaemia is treated in hospital with intravenous calcium. Chronic management is oral calcium + activated vitamin D, balanced against urine calcium to protect the kidneys from stones and nephrocalcinosis. Mediora.AI flags the calcium-PTH pattern; treatment titration requires endocrinology.