In neonates, the symptoms of hyperparathyroidism are
respiratory distress, cyanosis, apnea, hypertonia, agitation, and tetany.
In infants, the symptoms are seizures and tinnitus crisis with inspiratory stridor,
laryngospasm, and unexplained tachycardia. In children, tinnitus is the most frequent
sign, with seizures that can be typical or not. Hypocalcemia may be
life-threatening and can cause nephrocalcinosis and renal lithiasis.