Question 25

List 5 major causes and 3 important clinical manifestations of hypocalcaemia in the critically ill patient.

College Answer

Aetiology

Calcium chelation (eg. alkalosis, citrate toxicity, tumour lysis, rhabdomyolysis)

Drug induced (eg. phenytoin, diphosphonates)

Hypoparathyroidism (eg. hypo and hypermagnesemia, sepsis, surgerical removal) Hypovitaminosis D (eg. inadequate intake, malabsorption, liver disease)

Reduced bone turnover (eg. osteoporosis, elderly, cachexia)

Clinical manifestations

Central nervous system (eg. circumoral and peripheral paraesthesia, muscle cramps, tetany, seizures, psychosis)

Cardiovascular (eg. arrhythmias, hypotension, inotrope unresponsiveness, prolonged QT intervals)

Respiratory (eg. apnoea, laryngospasm, bronchospasm)

Here, I will reproduce the tables for the aetiologies of hypocalcemia and its clinical manifestations.

Causes of Hypocalcemia
Low Parathyroid Hormone Primary hypoparathyroidism (i.e. destruction of the parathyroid glands) Post-operative hypoparathyroidism Hungry bone syndrome HIV infection Haemochromatosis	High or normal Parathyroid hormone Vitamin D deficiency Hypomagnesemia Hyperphosphataemia Renal failure (pseudohypoparathyroidism) Tumour lysis syndrome Acute pancreatitis Alkalosis Depletion in coagulopathy Drugs Phenytoin Fluoride toxicity Foscarnet EDTA Citrate Phosphate Bisphosphonates

Clinical Manifestations of Hypocalcemia
Mild hypocalcemia Generalised myalgia Twitching, fasciculations QT prolongation Chvostek’s sign Confusion, delirium, psychosis	Severe hypocalcemia Carpopedal spasm (Trousseau’s sign) Tetany and seizures Papilloedema Cardiac arrhythmias, esp. Torsades Hypotension

UpToDate has a nice summary of this topic for the paying customer.

Cooper, Mark S., and Neil JL Gittoes. "Diagnosis and management of hypocalcaemia." BMJ: British Medical Journal 336.7656 (2008): 1298.

Tohme, J. F., and J. P. Bilezikian. "Hypocalcemic emergencies." Endocrinology and metabolism clinics of North America 22.2 (1993): 363-375.

Diercks, Deborah B., et al. "Electrocardiographic manifestations: electrolyte abnormalities." The Journal of emergency medicine 27.2 (2004): 153-160.