Paediatrics: Hypercalcaemia

2021-04-15 03:23 PM

There are a number of different causes of high plasma calcium levels: · William’s syndrome. · Idiopathic infantile hypercalcaemia.

Hypercalcaemia

 

There are a number of different causes of high plasma calcium levels:

 

  • William’s syndrome.

 

  • Idiopathic infantile hypercalcaemia.

 

  • Hyperparathyroidism.

 

  • 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.

 

Clinical features

 

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.

 

Investigations

 

Laboratory

 

  • Plasma calcium (total and corrected for albumin).

 

  • Serum PTH.

 

  • Vitamin D metabolites.

 

  • U&E/LFTs.

 

  • TFT.

 

  • Urinary calcium excretion (UCa:UCr ratio; 24hr UCa).

 

Radiological 

Renal US scan (screen for nephrocalcinosis).

 

Treatment

Chronic treatment 

Directed at the underlying cause.

Hyperparathyroidism

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.

  • hyperparathyroidism:
  • parathyroid adenoma;
  • parathyroid hyperplasia: MEN type 1; MEN type 2; neonatal severe form.
  • hyperparathyroidism:
  • hypocalcaemic states—rickets;
  • hyperphosphatemia—chronic renal failure.
  • Transient neonatal hyperparathyroidism: maternal hypoparathyroidism.

Primary hyperparathyroidism

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.