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Background: Hypocalcemia is a frequently observed clinical and laboratory abnormality in neonates with risk factors such as prematurity, infant of diabetic mothers and perinatal asphyxia. Hypocalcemia can be asymptomatic or can cause apnoea, seizures, jitteriness, stridor, cardiac abnormalities. Clinically as calcium levels are maintained within narrow ranges. It is therefore imperative to measure and correct any deficit at the earliest. Unfortunately, total serum calcium level correlates poorly with ionized calcium level. Measurement of ionized calcium is both time consuming and expensive and therefore the need for more rapid, inexpensive and non-invasive method for screening at risk-neonates. Serum calcium levels are known to affect the duration of the QoTc interval. Therefore establishing a good correlation between serum/ionized calcium levels and QoTc will validate ECG as a reliable marker of hypocalcemia. Objective was to find correlation between QoTc interval and serum calcium levels in sick neonates.Methods: Total 730 infants were for serum total calcium and ionized calcium levels. Off these 142 infants with hypocalcemia, 29 infants were excluded based on exclusion criteria. The remaining 113 neonates were subjected to three cycles of ECG measurement before correction of calcium and were taken as cases. QoTc intervals were measured and were correlated with corresponding serum total calcium and ionized calcium levels.Results: In this study, a moderate negative or downhill correlation was found between total serum calcium QoT (r = -0.694 and p = <0.001) and QoTc (r = -0.680 and p = <0.001). The ionized calcium levels were found to have strong negative or downhill correlation with QoT (r = -0.837 and p = <0.001), QoTc (r = -0.819 and p = <0.001). All these correlations were found to be statistically significant with p<0.05.Conclusions: QoTc interval can be used as a surrogate marker for blood total or ionized calcium levels.
RESUMO
PURPOSE: The clinical findings of early neonatal hypocalcemia are variable and it is difficult to find relationship between the symptoms and hypocalcemia due to complex causes. The purpose of this study is to establish the relationship between early neonatal hypocalcemia and clinical manifestations and to propose a guideline for appropriate treatment of early neonatal hypocalcemia, especially in asymptomatic cases. METHODS: Study subjects were all sick babies admitted to nursery and NICU and randornly selected 43 healthy babies at Sun General Hospital from January 1996 to December 1996. We examined serum calcium level within 72 hours after birth. Then we evaluated prospectively clinical findings according to each disease category in hypocalcemic cases and analysed the relationship of time course of clinical findings with hypocalcemia and compared serum calcium concentration followed by each therapy after 3 days. RESULTS: The results were as follows. 1) The incidence of early neonatal hypocalcernia was high in premature infants, low birth weight infants, infants with neonatal asphyxia, hyaline membrane disease and transient tachypnea. 2) Tremor, seizure, apnea, dyspnea, abdominal distension, cyanosis, and vomiting were frequently presented symptoms in early neonatal hypocalcemia. 3) In the cases of early hypocalcemia with symptoms, these symptoms persisted continuously after norrnalization of serum calcium concentration. 4) Among asymptomatic hypocalcernic group, mean serum calcium levels changed from 6.7 mg/dL to 8.7 mg/dL in 23 cases of no treatment, from 5.4 mg/dL to 10.3 mg/dL in 4 cases of calcium gluconate infusion, and from 6.3 mg/dL to 8.7 mg/dL in 7 cases of feeding low phosphorus containing milk. None persisted in hypocalcemic state irrespective of treatment methods. CONCLUSION: It is difficult to regard these symptoms as a rule to treatment because these symptoms were present after normalizaton of serum calcium concentration. In addition, asymptomatic hypocalcemia was improved shortly without any treatment without any problem. We conclude that for asymptomatic hypocalcemia, withholding dangerous calcium gluconate infusion would be perrnissible.