Hypocalcaemia and hypoparathyroidism

Hypoparathyroidism (HPTH) refers to underactivity or complete loss of the parathyroid glands. This most commonly arises following neck surgery, but congenital, auto-immune and genetic causes are also seen. The diagnosis is confirmed biochemically with hypocalcaemia, hyperphosphataemia and low parathyroid hormone levels.

 Baseline investigations - all patients

Full blood count

Useful indicator of general health and underlying disease. 

Urea and electrolytes

Addison's disease may be associated with autoimmune HPTH or with metastatic destruction and might be indicted by hyponatraemia and hyperkalaemia. Acute kidney injury may occur with over treatment of HPTH and hypercalcaemia. 

 

Liver function test  

Useful indicator of general health and underlying disease.

Bone profile

HPTH is usually associated with hypocalcaemia and hyperphsophataemia. Alkaline phosphatas levels may vary.

Hypercalcaemia may occur with subphysiological replacement. 

Parathyroid hormone

PTH is low with HPTH, with very high levels indicating vitamin D deficiency, or pseudohypoparathryoidism.

Vitamin D

Vitamin D deficiency is common, may cause hypocalcaemia and requires treatment in its own right.

Magnesium

Hypomagnesaemia is a common cause of apparent HPTH in adults and must be excluded before the diagnosis is confirmed. 

Further investigations - selected patients only

Electrocardiogram

ECG should be performed with patients presenting acutely unwell or with severe hypocalcaemia to exclude conduction disturbances. 

CT brain

CT scan may reveal basal ganglia calcification which may led to epilepsy particularly in patients with congenital HPTH.

Fasting glucose

This should be performed if diabetes is suspected.

Thyrotoxicosis may be associated with hypercalceamia acutely, but HPTH may be associated with immune thyroid conditions. 

Auto-antibody screen

An auto-antibody screen should be performed if the cause of HPTH is unclear or if other autoimmune conditions are suspected. 

 

9am cortisol or synacthen test

These should be performed if Addison's is suspected.

 

Renal ultrasound scan

This should be performed if the diagnosis of HPTH is confirmed, and will screen for renal dysgenesis, and form a baseline for future comparison. 

Hand X-ray

This is useful to confirm the clinical suspicion of shortened metacarpals in pseudohypoparathyrodism. 

 

Echocardiogram

Patients with suspected di George syndrome require echocardiography to seek other associated abnormalities. 

Bone scan

This should be performed if the diagnosis of HPTH is confirmed.

24-houry urinary calcium

This may be useful to exclude iatrogenic hypercalciuria during treatment.

Genetic testing

If an inherited cause is suspected, patients should be referred for genetic counselling and testing. 

Long term treatment of hypoparathyroidism

Long term treatment aims to control symptoms, with a serum calcium just below or at the bottom of the normal range: typically 2.0-2.25mmol/l, to prevent iatrogenic complications such as renal stones.