Transient late neonatal hypocalcemia with high serum parathyroid hormone

Three cases of transient neonatal pseudohypoparathyroidism

Neonatal hypocalcemia is defined as serum calcium (S-Ca) < 2.0 mmol/l in full-term newborns and <1.75 mmol/l in preterm newborns. Neonatal hypocalcemia is either early onset (<3 days of age) or late onset (>3 days of age). Newborns with hypocalcemia are often asymptomatic but may present with hypotonia, apnea, poor feeding, jitteriness, seizures, and cardiac failure. Signs of hypocalcemia rarely occur unless S-Ca drops below 1.75 mmol/l. Neonatal hypocalcemia can be a result of hypoparathyroidism (transient or primary), increased serum calcitonin, sepsis, asphyxia, hepatopathy, hypomagnesemia, high phosphate load, transient hypoparathyroidism, and, rarely, transient neonatal pseudohypoparathyroidism [transient resistance to biological actions of parathyroid hormone (PTH)]. We present the case of three boys (two with gestational age 39 weeks, one 36 weeks; none of them with either asphyxia or sepsis) with mild hypotonia, where S-Ca in the range of 1.67-1.9 mmol/l was detected within the first 3 days of life, together with hyperphosphatemia [serum phosphate (P) 2.5-2.6 mmol/l], normomagnesemia [serum magnesium (S-Mg) 0.77-0.88 mmol/l], normal alkaline phosphatase (ALP) activity (2.8-4.5 μkat/l), and high serum PTH (40-51 pg/ml; normal = 5-28). In spite of the gradual increase of S-Ca, the elevated serum PTH persisted beyond days 3, 4, and 6 in all three boys, together with normal or low-to-normal S-Ca, high or normal-to-high serum P, and no increases in serum ALP. The mothers S-Ca, P, Mg, ALP, and PTH levels were within normal reference ranges. With regard to laboratory results, the diagnosis of transient neonatal pseudohypoparathyroidism (due to immaturity of PTH-receptors) is highly probable in these three neonates.

Transient neonatal hypocalcemia: presentation and outcomes

OBJECTIVE

To determine the incidence of moderate-to-severe transient neonatal hypocalcemia in term neonates and to describe the characteristics of affected infants and the outcomes of their management.

METHODS

We reviewed medical records of all term infants <31 days of age who presented to Children's Medical Center Dallas from 2001 to 2009 with hypocalcemia (ionized calcium <1.00 mmol/L [4.00 mg/dL]).

RESULTS

Seventy-eight infants met criteria. Median (interquartile range) age at admission was 8.0 (7.0-10.0) days, and median duration of admission was 3.0 (2.0-4.0) days. Most infants were male (71.8%) and Hispanic (62.8%). Neonates were generally severely hypocalcemic and hyperphosphatemic. Seventy-five of 78 were hypomagnesemic, and the majority had low or inappropriately normal parathyroid hormone responses. Levels of 25-hydroxyvitamin D were ≤ 62.4 nmol/L (25 ng/mL) in all 42 infants in whom they were determined. All infants responded to therapy of limited duration with 1 or more of the following: calcium supplements, calcitriol, low phosphorus formula, and magnesium supplementation. Neuroimaging did not affect management decisions in any neonate.

CONCLUSIONS

Moderate-to-severe late-onset neonatal hypocalcemia is more common in Hispanic and male infants, is often a sign of coexistent vitamin D insufficiency or deficiency and hypomagnesemia, and is readily managed with therapy of limited duration. Neonates presenting with seizures who are found to be hypocalcemic are unlikely to benefit from neuroimaging evaluations.

Calcinosis cutis in a newborn with transient pseudohypoparathyroidism

Pseudohypoparathyroidism (PHP) is a heterogenous group of disorders characterized by hypocalcemia with hyperphosphatemia, increased serum concentration of parathyroid hormone (PTH), and insensitivity to the biological activity of PTH. Calcinosis cutis, the cutaneous deposition of calcium salts in the dermis, is a rare clinical symptom in infancy. The deposition of calcium in the skin may be classified as dystrophic, metastatic, idiopathic, and iatrogenic. Although a few infants with PHP and calcinosis cutis have been reported, to the authors' knowledge, the combination of neonatal transient PHP and calcinosis cutis associated with calcium treatment has not been previously reported. The authors report a newborn boy with transient PHP presenting with early hypocalcemia, hyperphosphatemia, increased PTH levels, and calcinosis cutis after intravenous treatment of calcium gluconate.

Transient pseudohypoparathyroidism as a cause of late-onset hypocalcemia in neonates and infants

BACKGROUND/PURPOSE

Transient pseudohypoparathyroidism is a rare cause of late-onset hypocalcemia in neonates and infants. The purpose of this study was to investigate the clinical presentation and natural course of transient pseudohypoparathyroidism in neonates and infants.

METHODS

From 1995 to 2006, 21 patients under 3 months of age were admitted to our department because of late-onset neonatal hypocalcemia. Among these, five were noted to have transient hypocalcemia, hyperphosphatemia and elevated serum parathyroid hormone levels. Their clinical data, biochemical findings and natural course were thoroughly analyzed.

RESULTS

All five patients were boys with increased neuromuscular irritability as their initial clinical manifestation. Initial biochemical data showed calcium 1.5 +/- 0.16 mmol/L, phosphorus 9.6 +/- 1.5 mg/dL, intact parathyroid hormone 182 +/- 93 pg/mL and tubular reabsorption of phosphorus 94.8 +/- 3.7%. Two of the patients had magnesium deficiency. After reduction of phosphorus intake and supplementation with calcium and/or magnesium as indicated, the biochemical derangements resolved in 28 +/- 3 days.

CONCLUSION

Neuromuscular irritability is usually the initial clinical presentation of transient pseudohypoparathyroidism. Aside from delayed renal maturation, pseudohypoparathyroidism is also caused by magnesium deficiency. Such a disturbance usually resolves before 3 months of age.