<prompt> Which one of the following features may NOT be seen in hypocalcemiatetany?prolongation of QTCataract formationClotting defectsIntestinal biliary colic  <response>: 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 dont 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. 