- Overview
- Causes hyper-calaemia with low urine calcium secretion
- Autosomally dominantly
- Mutation for a gene in the calcium sensing receptor expressed in the parathyroid tissue and kidney tissue.
- Clinical
- Because the calcium receptors aren’t sensing calcium, there is an inappropriate amount of PTH release by the parathyroid, and an inappropriate amount of calcium is re-absorbed in the kidney.
- Typically patients are asymptomatic with a high calcium
- Rarely can get symptoms of high ca – weakness, fatigue, thirst, abdominal pain, constipation, pancreatitis, renal stones, bony pain, renal failure.
- Diagnosis
- High serum calcium with inappropriately normal or elevated PTH
- 24-hour urinary calcium excretion is typically below 200 mg/day (5 mmol/day)
- Calculation of the Ca/Cr (calcium/creatinine) clearance ratio less than 0.01
- Check Vitamin D deficient
- Stop thiazide diuretics
- Management
- Calcimimetics – sensitizes the calcium receptor thus reducing PTH excretion and increasing renal calcium excretion
- Surgery not indicated unless in the rare event of sequele e.g. pancreatitis