Endocrine Abstracts

Many laboratories offer a simple ratio of total testosterone (T):SHBG as an index (FAI) of free androgens. Methods for measuring free T (fT) are time consuming (equilibrium dialysis, ED) or reveal concentrations at odds with accepted values (RIA). The validity of FAI has been questioned and an alternative assessment by computation of fT recommended (1). We use a simpler calculation (2) producing results comparable to established literature. We have compared results obtained by...

Background: Among infants presenting with prolonged hyperbilirubinaemia there is anecdotal evidence that some babies who were Newborn Screening-negative for congenital hypothyroidism (CHT) have CHT diagnosed at the time of presentation with jaundice.Aims: To determine the prevalence of CHT in babies presenting with prolonged jaundice and to assess the predictive value of lowering the TSH cut-off for a screen-positive result on the ability to identify bab...

The human CYP17A1 enzyme exerts two activities, 17a-hydroxylase and 17,20 lyase, catalysing key steps in human adrenal steroid biosynthesis. An in frame deletion of 3 bp in exon 1 of the CYP17A1 gene, resulting in the loss of phenylalanine in position 53 (F53del), is one of the first CYP17A1 mutations described (JBC 1989, 264:18076). Reported patients have invariably presented with severe hypokalaemic hypertension, reflecting 17α-hydoxylase deficiency, and s...

Without adequate treatment patients with acromegaly die prematurely from cardiovascular disease (CVD); however the contribution of atherosclerosis in this process is controversial. Increased carotid IMT is an early morphological marker of atherosclerosis and predictor of subsequent cardiovascular events. Contradictory data exist regarding IMT in patients with acromegaly.We measured carotid IMT in 79 patients with acromegaly (47 male, mean age 55±14 ...

Congenital adrenal hyperplasia (CAH) caused by mutations in the electron donor enzyme P450 oxidoreductase (POR) is unique amongst all CAH variants in that it can be associated with ambiguous genitalia (disordered sex differentiation, DSD) both in 46,XX and 46,XY individuals. POR has a pivotal role in facilitating electron transfer from NADPH to microsomal P450 enzymes, including CYP17, which catalyses a key step in human androgen synthesis, the conversion of 17-hydroxypregneno...

P450 oxidoreductase (POR) has a pivotal role as electron donor to all cytochrome P450 enzymes that are microsomally located, i.e. CYP type II enzymes. Importantly, those include key enzymes involved in glucocorticoid and sex steroid biosynthesis such as CYP17 and CYP21. In addition, the activity of hepatic CYP enzymes involved in drug metabolism and detoxification also crucially depend on the transfer of electrons from NADPH via POR. Recently, mutations in P450 oxidoreductase ...

P450 Oxidoreductase Deficiency (ORD) is a novel form of congenital adrenal hyperplasia with biochemical evidence of combined 21-hydroxylase and 17α-hydroxylase deficiency. Mutations in P450 oxidoreductase (POR), a crucial electron donor to microsomal P450 enzymes including CYP17 and CYP21, have recently been identified as the cause of disease. Clinical features in ORD include ambiguous genitalia, glucocorticoid deficiency and craniofacial malformations resembling the Antl...

Background: The 3 day human chorionic gonadotrophin (HCG) test is commonly performed to investigate male undervirilisation. However, the utility of routine HCG testing for male undervirilisation in early childhood and correlation with pubertal progress is unclear.Aims: To review performance of the 3 day HCG test for diagnosis and outcomes.Methods: Standard 3 day HCG test data were analysed in 130 boys of age <3 years with under...

Background: Harrington et al.1 suggest that basal LH of ≥0.3 IU/l as measured by ICMA (Immulite 2500) has 100% specificity and 90.5% sensitivity in identifying progressive central precocious puberty (CPP).Aims: To examine the utility of basal LH measured with the DELFIA assay for identifying CPP in girls.Methods: All girls under age 9 years (median 7.3 years) investigated for precocious puberty with a GnRH...

Background: The standard dose Synacthen test (SDST) is commonly used to identify glucocorticoid deficiency. A subnormal SDST in young infants raises the possibility of adrenal insufficiency (AI) due to pathology such as congenital adrenal hyperplasia (CAH). A physiological delay in maturation of adrenal glucocorticoid secretion may be another explanation especially in asymptomatic infants with a transiently subnormal SDST.Aims: To review the diagnoses an...