There are a number of different causes of high plasma calcium levels: · William’s syndrome. · Idiopathic infantile hypercalcaemia.
There are a number of different causes of high plasma calcium levels:
- William’s syndrome.
- Idiopathic infantile hypercalcaemia.
- Hypercalcaemia of malignancy.
- Vitamin D intoxication.
- Familial hypocalciuric hypercalcaemia.
Other uncommon causes include: sarcoidois and other granulomatous disease; chronic immobilization; renal failure; hyperthyroidism; Addison’s disease; iatrogenic, e.g. thiazide diuretics.
Symptoms and signs of hypercalcaemia are non-specific.
- GI: anorexia; nausea and vomiting; failure to thrive; constipation;abdominal pain.
- Renal: polyuria and polydipsia.
- CNS: apathy; drowsiness; depression.
- Plasma calcium (total and corrected for albumin).
- Serum PTH.
- Vitamin D metabolites.
- Urinary calcium excretion (UCa:UCr ratio; 24hr UCa).
Renal US scan (screen for nephrocalcinosis).
Directed at the underlying cause.
Uncommon in children, excessive production of PTH may result from a primary defect of the parathyroid glands or may be secondary and compensatory to either hypocalcaemia or hyperphosphataemic states.
- p hyperparathyroidism:
- parathyroid adenoma;
- parathyroid hyperplasia: MEN type 1; MEN type 2; neonatal severe form.
- s hyperparathyroidism:
- hypocalcaemic states—rickets;
- hyperphosphatemia—chronic renal failure.
- Transient neonatal hyperparathyroidism: maternal hypoparathyroidism.
Rare in children. In the neonatal period it usually associated with generalized parathyroid hyperplasia. In older children it is usually due to a parathyroid adenoma and most often associated with MEN type 1.
Transient neonatal hyperparathyroidism
Observed in neonates born to mother with previously undetected and/ or untreated hypoparathyroidism or pseudohypoparathyroidism. Chronic intrauterine hypocalcaemia results in hyperplasia of the foetal parathyroid glands.
Neonatal severe hyperparathyroidism
See Familial hypocalciuric hyper-calcaemia.
Hypercalcaemia of malignancy
Rarely, in children with endocrine tumours (e.g. phaeochromocytoma) or other tumours (e.g. lymphoma), production of humoral factors such as PTH-related peptide (PTHrP) results in hypercalcaemia.
Treatment requires resection and removal of the tumour to reverse the hypercalcaemic state. Interim control can be achieved with a single IV infusion of a bisphosphonate agent, e.g. pamidronate. The latter enhances calcium bone resorption.
Familial hypocalciuric hypercalcaemia
Autosomal dominant disorder caused by a mutation of the calcium-sensing receptor (CaSR) gene. This is a benign, mostly asymptomatic disorder, which is often an incidental finding during routine biochemistry analysis. Plasma calcium levels are raised (but usually <3mmol/L), and urinary calcium excretion is low. PTH levels are inappropriately normal for the degree of hypercalcaemia.