Test Findings
 

Hypocalcaemia

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Overview

  • Hypocalcaemia refers to a reduced serum calcium concentration. This may occur due to disorders related to parathyroid hormone, vitamin D or bone metabolism.
    • Look For

    • Total calcium <2.15 mmol/L
    • Ionised calcium < 1.15 mmol/L

Aetiology

    • Causes of Hypocalcaemia

    • Hypoparathyroidism - iatrogenic, autoimmune, congenital
    • PTH resistance - pseudohypoparathyroidism, hypomagnesaemia
    • Vitamin D deficiency - inadequate intake, low sun exposure, malabsorption, liver failure, chronic kidney disease
    • Increased excretion / reduced bony turnover - loop diuretics, osteoporosis, cachexia, bisphosphonates, malignancy
    • Extravascular calcium buildup - osteoblastic metastases, sepsis, pancreatitis
    • Calcium chelation - alkalosis, citrate, EDTA, hyperphosphataemia
    • Genetic - familial hypoparathyroidism, DiGeorge syndrome

Clinical Features

    • Signs and Symptoms

    • Hyperreflexia
    • Tetany (Chvostek’s & Trousseau’s signs)
    • Seizures
    • Heart failure (due to reduced  contractility)
    • ECG Changes

    • Prolonged QT
    • Torsade de pointes (rare, even with severe hypocalcaemia)

Approach

  • Check the patient's PTH, phosphate, vitamin D and magnesium levels. If a cause is not evident and hypocalcaemia is ongoing (i.e. not lab error) then further investigation may be warranted.
    • Approach
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