|Familial hypocalciuric hypercalcaemia (FHH)
Hypoparathyroidism most commonly results from anterior neck surgery, constituting 75% of all cases
- Hypoparathyroidism is a rare disorder
- See Articles on Hypocalcaemia
- Low levels of PTH due to various causes
- Low Calcium, High Phosphate, Normal alkaline phosphate
- Primary: Autoimmune, Genetic, idiopathic and autoimmune aetiologies, DiGeorge's syndrome, Bartter's syndrome
- Secondary: Radiation, Surgery (thyroidectomy/parathyroidectomy), hypomagnesaemia
- Hypocalcemia (albumin-adjusted) confirmed on at least two occasions separated by at least 2 weeks.
- PTH concentration, by second- or third-generation immunoassay, that is undetectable or inappropriately low (ie, <20 pg/mL) in the presence of hypocalcemia on at least two occasions.
- Phosphate levels in the upper normal or frankly elevated range (helpful but not mandatory).
- After neck surgery, chronic hypoparathyroidism is established only after 6 months.
- Increased neuromuscular irritability caused by hypocalcaemia
- Tingling, muscle cramps and seizures, stridor.
- Calcifications in the basal ganglia in particular
- Nephrocalcinosis and calcium deposits in joints, eyes, skin, vasculature
- FBC, U&E, Creatinine, Mg - Exclude hypomagnesaemia
- Low Calcium, High Phosphate, Low PTH
- Prolonged QTc on electrocardiogram
- Vitamin D: 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D
- 24-hour urine for creatinine clearance or eGFR, calcium excretion, and biochemical stone risk profile
- Target organ imaging: X-ray (skull), Renal USS or CT
- BMD by dual-energy x-ray absorptiometry
- Replace magnesium if low magnesium levels
- Activated vitamin D and/or calcium supplements: 1,25(OH)D is given
- Thiazide diuretics to manage hypercalciuria and low salt diet
- Phosphate binders and low phosphate diet, to control hyperphosphatemia
- PTH replacement has emerged as a new treatment option