Which is not true of hypocalcaemia –
Correct Answer: Inverse relation with Mg++ levels
Description: Hypocalcaemia is low calcium levels in the blood serum.The normal range is 2.1-2.6 mmol/L (8.8-10.7 mg/dl, 4.3-5.2 mEq/L) with levels less than 2.1 mmol/l defined as hypocalcemia.Mildly low levels that develop slowly often have no symptoms.Otherwise symptoms may include numbness, muscle spasms, seizures, confusion, or cardiac arrest Common causes include hypoparathyroidism and vitamin D deficiency.Others causes include kidney failure, pancreatitis, calcium channel blocker overdose, rhabdomyolysis, tumor lysis syndrome, and medications such as bisphosphonates.Diagnosis should generally be confirmed with a corrected calcium or ionized calcium level.Specific changes may be seen on an electrocardiogram (ECG). Initial treatment for severe disease is with intravenous calcium chloride and possibly magnesium sulfate.Other treatments may include vitamin D, magnesium, and calcium supplements. If due to hypoparathyroidism, hydrochlorothiazide, phosphate binders, and a low salt diet may also be recommended.About 18% of people who are being treated in hospital have hypocalcemia The neuromuscular symptoms of hypocalcemia are caused by a positive bathmotropic effect (i.e. increased responsiveness) due to the decreased interaction of calcium with sodium channels. Since calcium blocks sodium channels and inhibits depolarization of nerve and muscle fibers, reduced calcium lowers the threshold for depolarization.The symptoms can be recalled by the mnemonic "CATs go numb" - convulsions, arrhythmias, tetany, and numbness in the hands and feet and around the mouth. Petechiae which appear as on-off spots, then later become confluent, and appear as purpura (larger bruised areas, usually in dependent regions of the body). Oral, perioral and acral paresthesias, tingling or 'pins and needles' sensation in and around the mouth and lips, and in the extremities of the hands and feet. This is often the earliest symptom of hypocalcaemia. Carpopedal and generalized tetany (unrelieved and strong contractions of the hands, and in the large muscles of the rest of the body) are seen. Latent tetany Trousseau sign of latent tetany (eliciting carpal spasm by inflating the blood pressure cuff and maintaining the cuff pressure above systolic) Chvostek's sign (tapping of the inferior poion of the cheekbone will produce facial spasms) Tendon reflexes are hyperactive Life-threatening complications Laryngospasm Cardiac arrhythmias Ref Davidson 23rd edition pg 370
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