Detection of early onset neonatal hypocalcaemia in low birth weight infants by Q-Tc and Q-oTc interval measurement.

In 26 infants born in the 28th to 34th (mean 32nd) week of gestation, with a weight ranging from 1130 to 1980 (mean 1560) g, the correlation between the plasma level of total calcium and the Q-Tc and Q-oTc ECG intervals was studied within 72 (mean 12.5) hours after birth. The Q-Tc interval correlated with the total calcium (r = -0.41, p less than or equal to 0.01) and so did the Q-oTc interval (r = 0.56, P less than or equal to 0.01). Sensitivity of the detection of hypocalcaemia when using the Q-Tc interval sensitivity was 77% and specificity 94.4%. After administration of calcium to five infants suffering from an early form of symptomatic hypocalcaemia, a shortening of the corrected intervals occurred in four cases, while in one a paradoxical prolongation ensued. The changes were not seen on the display. The use of Q-oTc is suitable for the screening of early hypocalcaemia in low birth weight infants and it allows a timely initiation of therapy without delay.