Which one of the following features may NOT be seen in hypocalcemia/tetany?
Features of tetany / decrease Ca++: - Causes increased neuronal membrane permeability to Na+ ions, allowing easy initiation of action potentials. Consequently, hypocalcemia causes tetany, it also occasionally causes seizures. Decreased Ca++ levels lead to prolonged electrical activity in hea, ventricular depolarization will be prolonged because of the less Ca++. Cataract, paicularly the nuclear cataracts have been the features of chronic decrease in Ca++. Serum Ca++ is necessary for stability of Na++ gates in the nerve membranes, in case of decrease Ca++ levels, Na+ gates become unstable & they excessively fire, this event in smooth muscle of GIT can lead to intestinal & biliary spasm (colicky). Blood clotting need Ca++, this ionic Ca++ required for every step of intrinsic & extrinsic pathway, except for initial two steps in intrinsic pathway, but this ionic Ca++ is needed in small amounts. For clotting process very less Ca++ is needed, so, clotting defect usually don't get associated with decrease Ca++. Tetany occur when S. Ca++ decreases below 6 mg / dl. Lethal level of Ca++ below 4 mg / dl (death by laryngeal spasm).
prolongation of QT
Cataract formation
Clotting defects
Intestinal & biliary colic
Endocrine System