Near-fatal misdiagnosis of congenital adrenal hyperplasia

Severe asymptomatic maternal antepartum hyponatremia leading to neonatal seizures: prevention is better than cure

Background

Pre-delivery maternal electrolyte derangements may reflect themselves in the newborn, since placental homeostasis determines electrolyte equilibrium between mother and fetus.

Case presentation

A term newborn, transferred to our Neonatal Intensive Care Unit 1 h after birth for an apnoea episode, presented with initially left-sided, and subsequently generalized tonic-clonic seizures due to severe hyponatremia (119 mmol/L). Seizures rapidly ceased after electrolyte correction plus a phenobarbital bolus. Deep hyponatremia was also detected in the mother (123 mmol/L).

Conclusions

As placental homeostasis determines electrolytes equilibrium between mother and fetus, obstetrics and neonatologists should be aware that any maternal dyselectrolytemia will reflect itself in the newborn; hence, it is fundamental to detect possible maternal electrolyte imbalances before delivery, in order to be prepared to timely correction of electrolyte derangements in the newborn.

Pseudohypoaldosteronism without nephropathy masking salt-wasting congenital adrenal hyperplasia genetically confirmed

Salt-losing crisis with hypoglycaemia and shock are the main manifestations of congenital adrenal hyperplasia (CAH) during the first weeks of life, while hyponatremia and hyperpotassemia alone are seen on mineralocorticoid deficiency or resistance. During the neonatal period, high blood levels of adrenal steroids may lead to confusing laboratory tests not being able to identify the real level of each hormone. A 33-day-old male baby was admitted at the emergency department with severe salt-losing crisis (Na(+) 99 mEq/l and K(+) 9.4 mEq/l) and mild acidosis. No hypoglycaemia or hypotension was seen. Urinary tract infection was excluded. Despite treatment with hydrocortisone and fludrocortisone, hyperpotassemia was hard to control. Laboratory tests could not differentiate between pseudohypoaldosteronism and CAH as both the aldosterone (2454 pg/ml) and 17-OH-progesterone (656.6 ng/ml) levels were high. Diagnosis was made, thanks to the genetic study that proved classical mutations in both alleles of the 21-hydroxylase gene.

Maternal water intoxication as a cause of neonatal seizures

A term infant was admitted at 6 h of age with seizures related to hyponatraemia. During the last hours of labour the infant's mother had drunk 3 L of water. After delivery the serum sodium was 121 mmol/L in the mother and 126 mmol/L in the infant. Both resolved spontaneously. We discuss this case and the impact of maternal fluid intake during labour on the fetus and neonate. Women should be advised that excessive oral fluid intake during labour could adversely affect both mother and infant.

The diagnosis of congenital adrenal hyperplasia in the newborn by gas chromatography/mass spectrometry analysis of random urine specimens

Definitive neonatal diagnosis of congenital adrenal hyperplasia (CAH) is frequently complicated by normal 17-hydroxyprogesterone levels in 21-hydroxylase-deficient patients, residual maternal steroids, and other interfering substances in neonatal blood. In an effort to improve the diagnosis, we developed a gas chromatography/mass spectrometry method for simultaneous measurement of 15 urinary steroid metabolites as early as the first day of life. Furthermore, we developed 11 precursor/product ratios that diagnose and clearly differentiate the four enzymatic deficiencies that cause CAH. Random urine samples from 31 neonatal 21-hydroxylase-deficient patients and 59 age-matched normal newborns were used in the development. Additionally, samples from two 11 beta-hydroxylase-deficient patients and one patient each for 17 alpha-hydroxylase and 3 beta-hydroxysteroid dehydrogenase deficiencies were used. The throughput for one bench-top gas chromatography/mass spectrometry instrument is 20 samples per day. Thus, this method affords an accurate, rapid, noninvasive means for the differential diagnosis of CAH in the newborn period without the need for invasive testing and ACTH stimulation.

A new specific and sensitive time resolved-fluoroimmunoassay of 11-deoxycortisol in serum

A biotinylated 11-deoxycortisol tracer was synthesized from 11-deoxycortisol-3-carboxymethyloxime and the conjugate obtained by acylation of biotinylaminopropylammonium trifluoroacetate. This biotinylated tracer was used to develop an 11-deoxycortisol time-resolved-fluoroimmunoassay (TR-FIA). The tracer was quantified after adding streptavidine-Europium. A TR-FIA sensitive standard curve, with displacement of 20, 50, and 80% of tracer was obtained with 12.4, 70.7, and 512.8 pg of 11-deoxycortisol, respectively. After extraction followed by Celite chromatography, purified serum samples were simultaneously assayed by RIA and TR-FIA. The results obtained by the two methods were practically identical, however, this new specific, non-isotopic 11-deoxycortisol assay has the advantage of being more sensitive than RIA, thus well-suited to accurate measurement in endocrinological studies, particularly when serum 11-deoxycortisol levels in patients are just above the highest normal values. Moreover, this non-isotopic assay is cheaper than RIA.

Combined 21-hydroxylase and 11beta-hydroxylase deficiency: patient report and molecular basis

A female newborn (46, XX) with ambiguous genitalia was initially diagnosed by biochemical criteria as having classical congenital adrenal hyperplasia caused by 11beta-hydroxylase deficiency. Shortly after effective treatment was administered, she developed a salt-wasting crisis with severe electrolyte imbalance. DNA analysis revealed a homozygous splice mutation in the second intron of the CYP21 gene, for which both parents were heterozygous. No mutations were found in the entire CYP11B1 gene, thus proving that the 11beta-hydroxylase deficiency was not caused by a gene mutation but rather was a secondary event, possibly due to androgen suppression of 11beta-hydroxylase activity.

Congenital adrenal hyperplasia due to 21-hydroxylase deficiency

More than 90% of cases of congenital adrenal hyperplasia (CAH, the inherited inability to synthesize cortisol) are caused by 21-hydroxylase deficiency. Females with severe, classic 21-hydroxylase deficiency are exposed to excess androgens prenatally and are born with virilized external genitalia. Most patients cannot synthesize sufficient aldosterone to maintain sodium balance and may develop potentially fatal "salt wasting" crises if not treated. The disease is caused by mutations in the CYP21 gene encoding the steroid 21-hydroxylase enzyme. More than 90% of these mutations result from intergenic recombinations between CYP21 and the closely linked CYP21P pseudogene. Approximately 20% are gene deletions due to unequal crossing over during meiosis, whereas the remainder are gene conversions--transfers to CYP21 of deleterious mutations normally present in CYP21P. The degree to which each mutation compromises enzymatic activity is strongly correlated with the clinical severity of the disease in patients carrying it. Prenatal diagnosis by direct mutation detection permits prenatal treatment of affected females to minimize genital virilization. Neonatal screening by hormonal methods identifies affected children before salt wasting crises develop, reducing mortality from this condition. Glucocorticoid and mineralocorticoid replacement are the mainstays of treatment, but more rational dosing and additional therapies are being developed.