In preterm newborns, secondary hyperparathyroidism (HPTH) is an underdiagnosed and undertreated entity. Its detection in the context of metabolic bone mineral disease (MBD) screening programs may be important to guide nutritional treatment. We designed a retrospective cohort study to determine the incidence of HPTH in very premature infants. As secondary objectives, we studied the risk factors, morbidities, and biochemical alterations associated with HPTH. A total of 154 preterm newborns ≤32 weeks gestational age (GA) were included. Of these, 40.3% (n = 62) presented with HPTH. In the multivariate analysis, independent risk factors for HPTH were cesarean section (OR: 4.00; 95% CI: 1.59-10.06), oxygen during resuscitation (OR: 3.43; 95% CI: 1.09-10.81), invasive mechanical ventilation (OR: 3.56; 95% CI: 1.63-7.77) and anemia requiring transfusion (OR: 2.37; 95% CI: 1.01-5.57). Among the analytical variables, serum calcium (OR: 0.53; 95% CI: 0.29-0.97), serum phosphate (OR: 2.01; 95% CI: 1.39-2.92), vitamin D (OR: 0.96; 95% CI: 0.93-1), and the calcium/creatinine ratio in urine (OR: 0.05; 95% CI: 0.01-0.28) were independently associated with HPTH. The simplified predictive model included GA and calcium/creatinine ratio in urine and demonstrated an AUC of 0.828. We concluded that HPTH is a frequent entity among very premature infants and that further studies are required to determine the role of HPTH in MBD and the clinical applicability of prediction models.
Keywords: calcium; metabolic bone disease; parathyroid hormone; phosphorus; prematurity.