The changing role of the clinical laboratory in the investigation of polycystic ovarian syndrome

In this review we outline clinical features, presentation and pathogenesis of polycystic ovarian syndrome (PCOS), treatment objectives and therapeutic options. We focus on and outline the changing role of the clinical laboratory in diagnosis and treatment of this condition. We also review recent information on the involvement of insulin resistance in the syndrome. We provide some explanation for confusion over the selection of the best hormone measurements for diagnosis. Finally, we outline the best current and future laboratory support for this common condition in young women.

Benefits of salmon eating on traditional and novel vascular risk factors in young, non-obese healthy subjects

AIM

The present clinical study tested the hypothesis that oil-rich fish consumption improves CHD risk factors.

METHODS

Forty-eight (16 men) non-obese, healthy adults aged 20-55, consumed 125 g/day of salmon for a 4-week period followed by a 4-week period with no-fish (41 completers). Subjects were instructed to maintain dietary and physical activity patterns during the period of study. Blood pressure, anthropometric, body composition and dietary information with fasting blood samples to determine traditional and novel CHD risk markers and plasma fatty acids were obtained before and after each period.

RESULTS

Compared to no-fish, eating salmon significantly decreased systolic, diastolic and mean arterial blood pressure by 4%, triglycerides by 15%, and LDL-cholesterol by 7%, and significantly increased HDL-cholesterol by 5% (P<0.05). The changes in blood pressure and lipids alone with salmon intake predict around a 25% reduction in CHD risk based on the PROCAM risk calculator. Plasma adiponectin demonstrated a trend towards improvement (8.39 micromol/L with salmon and 7.52 with no-fish; P=0.086) but no significant changes were found either in plasma leptin, glucose or insulin after salmon consumption.

CONCLUSIONS

Daily consumption of salmon improves traditional risk predictors of CHD in non-obese subjects. Adiponectin may be involved but the impact on novel risk factors needs study in high-risk subjects.

Variability in hydrocortisone plasma and saliva pharmacokinetics following intravenous and oral administration to patients with adrenal insufficiency

OBJECTIVE

The best method for determining hydrocortisone replacement therapy is not well defined. This study aimed to assess interindividual variability in cortisol pharmacokinetics and to investigate whether measurement of salivary cortisol provides a useful alternative to plasma concentration measurements.

DESIGN

Intravenous (IV) and oral crossover.

PATIENTS

Twenty-seven patients with primary or secondary adrenal insufficiency who had been on stable replacement therapy for at least 3 months.

MEASUREMENTS

Plasma and salivary concentrations of cortisol were measured up to 8 h following administration of hydrocortisone.

RESULTS

After IV administration, Cmax ranged from 715 to 8313 nmol/l, area under the curve (AUC) from 1112 to 12 177 nmol h/l and cortisol clearance had a median (range) of 0.267 (0.076-0.540) l/h/kg. After oral administration, Cmax ranged from 422 to 1554 nmol/l, AUC 1081-5471 nmol h/l and oral clearance had a median (range) of 0.267 (0.081-0.363) l/h/kg. There was no clear relationship between paired saliva and plasma cortisol concentrations after IV or oral dosing. Plasma and salivary AUC(2-8 h) after IV administration were highly correlated (r2 = 0.77) but differences between predicted and measured plasma AUCs ranged from 3% to 90%. There was a poor correlation between plasma and saliva AUC(2-6 h) after oral administration (r2 = 0.16).

CONCLUSIONS

The wide interindividual variability in plasma and salivary profiles of cortisol following the administration of IV and oral hydrocortisone to patients with adrenal insufficiency and the poor correlation between salivary and plasma measurements suggest that salivary cortisol measurements cannot be used for individual hydrocortisone dosage adjustment.

Endogenous corticosteroid biosynthesis in subjects after bilateral adrenalectomy

OBJECTIVE

Corticosteroids can be synthesized in extra-adrenal tissues but the contribution of this to circulating levels in humans is not known. Previous in vitro studies suggest that the 'hybrid' corticosteroid 18-oxocortisol (18-oxoF) is produced from cortisol by aldosterone synthase. We looked for evidence of extra-adrenal production of this and other corticosteroids in 10 subjects stable on long-term glucocorticoid replacement following bilateral adrenalectomy.

METHODS

In phase 1, patients were maintained on cortisol alone (30 mg/day), in phase 2 dexamethasone (2 mg/day), and in phase 3, both cortisol and dexamethasone. Each phase lasted 3 days.

MEASUREMENTS

On the last day of each phase, 24-h urine collection was performed for analysis of steroid metabolite excretion [using gas chromatography-mass spectrometry (GCMS)] and plasma aldosterone and renin were measured (by radioimmunoassay).

RESULTS

Cortisol metabolite excretion rate [tetrahydrocortisone (THE) + tetrahydrocortisol (THF) + allotetrahydrocortisol (aTHF)] fell from 9169 nmol/24 h in phase 1 to 22 nmol/24 h in phase 2, rising to 6843 nmol/24 h in phase 3. Tetrahydroaldosterone (THAldo) excretion was readily detectable and did not alter significantly between phases (26.5, 23.5 and 28.5 nmol/24 h, respectively; P = 0.474). 18-Hydroxycortisol (18-OHF) excretion was easily detectable in phases 1 and 3 (252.5 and 212 nmol/24 h), falling in phase 2 (12 nmol/24 h). 18-oxoF excretion rates were lower but followed a similar pattern (1.62, 0.085 and 1.785 nmol/24 h in phases 1, 2 and 3, respectively).

CONCLUSIONS

Significant levels of adrenal steroids are found in adrenalectomized subjects. We speculate that this occurs at extra-adrenal sites or in residual adrenal cortex tissue in an ACTH-independent manner. Our data suggest that aldosterone synthase, acting on cortisol, is the source of 18-oxoF and 18-OHF in these subjects. Further studies of corticosteroid production within adrenalectomized subjects, looking for evidence of adrenal regrowth or residual adrenal tissue, are justified.

Systemic Inflammatory Response, Prostate-Specific Antigen and Survival in Patients with Metastatic Prostate Cancer

BACKGROUND

It is increasingly recognised that, in cancer patients, disease progression is dependent on a complex interaction of the tumour and the host inflammatory response and that the systemic inflammatory response, as evidenced by an elevated C-reactive protein (CRP) concentration, may be a useful prognostic factor.

MATERIALS AND METHODS

The prognostic value of CRP compared with prostate-specific antigen (PSA) was examined in 62 patients with metastatic prostate cancer receiving androgen-deprivation therapy.

RESULTS

In all, 41 (66%) of patients died, 38 (61%) of their disease. On univariate survival analysis, PSA (p < 0.05) and CRP (p < 0.05) were significant predictors of cancer-specific survival. On multivariate analysis, both PSA (HR 1.96, 95% CI 1.00-3.83, p = 0.049) and CR (HR 1.97, 95% CI 0.99-3.92, p = 0.052) were independent predictors of cancer-specific survival. PSA concentrations were significantly correlated with those of CRP (r(s) = 0.46, p < 0.001).

CONCLUSION

The results of the present study suggest that, in patients with metastatic prostate cancer, the presence of an elevated CRP concentration predicts poor outcome, independent of PSA.

Adiponectin and coronary heart disease: a prospective study and meta-analysis

BACKGROUND

There is uncertainty about the association between circulating concentrations of adiponectin and coronary heart disease (CHD) risk. We report new data from a prospective study in the context of a meta-analysis of previously published prospective studies.

METHODS AND RESULTS

We measured baseline adiponectin levels in stored serum samples of 589 men with fatal CHD or nonfatal myocardial infarction and in 1231 controls nested within a prospective study of 5661 men (aged 40 to 59 years) recruited during 1978-1980, as well as in paired samples obtained 4 years apart from 221 of these participants. Baseline adiponectin concentrations correlated (P < 0.0001) positively with HDL cholesterol (r = 0.33) and inversely with C-reactive protein (r = -0.11) and BMI (r = -0.21), and the year-to-year consistency of adiponectin values was comparable to those of blood pressure and total cholesterol levels. No significant difference between median adiponectin levels at baseline was observed between cases and controls (10.2 versus 10.8 microg/mL; P = 0.5), despite the fact that body mass index, HDL, and C-reactive protein were all significant predictors of events in this cohort. The odds ratio for CHD was 0.89 (95% CI, 0.67 to 1.18) in a comparison of men in the top third of adiponectin concentrations compared with those in the bottom third, similar to a meta-analysis (including the present study) of 7 prospective studies involving a total of 1318 CHD cases (odds ratio, 0.84 [95% CI, 0.70 to 1.01]).

CONCLUSIONS

In contrast to the strong associations previously reported between adiponectin levels and risk of type 2 diabetes, any association with CHD risk is comparatively moderate and requires further investigation.

Undetectable salivary testosterone in young women with premature ovarian failure

BACKGROUND

The extent of androgen deficiency in young women with premature ovarian failure (POF) is unclear.

AIM

Cross-sectional study of androgen status in young women with POF.

PATIENTS

Twenty women with POF: six had Turner syndrome (group A); eight had iatrogenic POF either secondary to bilateral oophorectomy or treatment of malignancy (group B); and six had idiopathic POF (group C). The median age was 30.5 years (range 19-39); in groups B and C the median duration of ovarian failure was 10.0 years (range 1-35).

METHODS

After a 2-month wash-out period without sex steroid replacement (SSR), serum testosterone (T), androstenedione (A4), dehydroepiandrosterone (DHEAS), SHBG, salivary testosterone (SalT) and the free androgen index [FAI = (serum T/SHBG) x 100] were measured.

RESULTS

Median serum A4 was 4.6 nmol/l (10th, 90th centiles, 3.6, 5.1) and DHEAS was 3.2 micromol/l (10th, 90th centiles, 2.3, 9.3). Although median serum T was relatively low at 1.4 nmol/l (10th, 90th centiles, 1.1, 1.7), median SHBG was also low at 34 nmol/l (10th, 90th centiles 22.2, 67.5) and the median calculated FAI was within the normal range at 3.7 (10th, 90th centiles, 2.3, 7.0). However, SalT was undetectable in almost all subjects in the three groups of POF.

CONCLUSIONS

Serum T and SHBG are relatively low in young women with POF and their FAI is therefore within the normal range. However, SalT, which measures free testosterone, is consistently low to undetectable in these young women with POF. The reliability of the FAI as a marker of androgen deficiency remains questionable.

Plasma leptin: associations with metabolic, inflammatory and haemostatic risk factors for cardiovascular disease

BACKGROUND AND AIM

Leptin, an adipocyte-derived protein, regulating food intake and metabolism has been implicated in the development of coronary heart disease. We have examined the relationship between leptin and vascular risk factors including insulin resistance, metabolic, inflammatory and haemostatic risk factors.

METHODS AND RESULTS

The study was carried out in 3640 non-diabetic men aged 60-79 years drawn from general practices in 24 British towns and who were not on warfarin. Leptin was strongly positively correlated with waist circumference (r=0.58; p<0.0001). Leptin concentrations decreased significantly with increasing physical activity and were lowered in cigarette smokers and elevated in men with pre-existing coronary heart disease and stroke; alcohol intake showed no association with leptin concentration. After adjustment for waist circumference and these lifestyle factors, increased leptin was independently associated with significant increases in insulin resistance, triglycerides, inflammatory markers (interleukin-6, C-reactive protein, fibrinogen, plasma viscosity), coagulation factor VIII, endothelial markers von Willebrand factor, tissue plasminogen activator, and fibrin D-dimer levels; and a decrease in HDL-cholesterol. No association was seen between leptin and blood pressure, total cholesterol, glucose or white cell count after adjusting for waist circumference. Further adjustment for insulin resistance abolished the relationships between leptin and triglycerides and HDL-cholesterol, weakened the associations with the haemostatic factors although they remained significant, but made minor differences to the associations with inflammatory markers.

CONCLUSION

Plasma leptin is associated with insulin resistance, inflammation and disturbances in haemostasis independent of waist circumference, suggesting possible pathways by which leptin may influence risk of cardiovascular disease.

Stability of housekeeping genes in alveolar macrophages from COPD patients

The stability of housekeeping genes is critical when performing gene expression studies. To date, there have been no studies that look at the stability of commonly used housekeeping genes in alveolar macrophages. Expression levels may be affected by culture, stimulation or disease severity. The present study investigated the expression level of 10 housekeeping genes and analysed the stability of their expression in alveolar macrophages from chronic obstructive pulmonary disease patients (n = 22) who were classified according to disease severity. Guanine nucleotide-binding protein, beta polypeptide 2-like 1 (GNB2L1), hypoxanthine phosphoribosyl transferase 1 (HPRT1) and ribosomal protein L32 (RPL32) were the most stably expressed in alveolar macrophages, irrespective of disease severity. There was no difference in the expression levels of 10 housekeeping genes between mild and moderate/severe patients. GNB2L1, HPRT1 and RPL32 were also stably expressed in alveolar macrophages cultured with no stimulation, or with interleukin-1beta, lipopolysaccharide or tumour necrosis factor-alpha stimulation. In conclusion, as fluctuations in the expression of some housekeeping genes were observed, including glyceraldehyde-3-phosphate dehydrogenase, it is recommended that guanine nucleotide binding protein, beta polypeptide 2-like 1 be used as a reference gene for alveolar macrophages in similar study designs, or that the stability of housekeeping genes be validated in alveolar macrophages prior to expression studies.

The utility of three different methods for measuring urinary 18-hydroxycortisol in the differential diagnosis of suspected primary hyperaldosteronism

OBJECTIVE

Urine 18-hydroxycortisol (18-OHF) measurements are claimed to discriminate between primary hyperaldosteronism due to Conn's syndrome/adrenal adenoma or idiopathic bilateral adrenal hyperplasia (BAH), and also to identify cases of glucocorticoid-suppressible hyperaldosteronism (GSH). We have evaluated three urine 18-OHF methods using a panel of urine samples from patients with hypertension.

DESIGN

Clinical methods comparative study.

METHODS

Urine samples from patients with primary hyperaldosteronism due to either adenoma (n = 6), BAH (n = 6), GSH (n = 9), or essential hypertension (n = 38) were analysed without knowledge of the diagnosis using three different methods in different laboratories. These included 'in-house' radioimmunoassay (RIA), 'in-house' time-resolved fluorometric assay (DELFIA), and gas chromatography mass spectrometry (GC-MS).

RESULTS

The three assays showed good correlation, but there were large bias differences: RIA bias was greater than DELFIA which was greater than GC-MS. Discrimination between adenoma and BAH patients was best for the DELFIA method, with no overlap between results for these two groups. All three methods gave significantly elevated results for the GSH group compared with the BAH and essential hypertension groups. No assay distinguished BAH from essential hypertension.

CONCLUSION

Measurement of urine 18-OHF may be a useful additional test in the differential diagnosis of primary hyperaldosteronism. The clinical diagnostic value of urinary 18-OHF measurements is method-dependent with the DELFIA assay having the best discriminatory value.

Efficacy and systemic tolerability of mometasone furoate and betamethasone sodium phosphate

This study evaluates the efficacy and systemic tolerability of licensed doses of mometasone furoate (Nasonex) and betamethasone sodium phosphate (Betnesol) in allergic chronic rhinosinusitis patients. It also assesses the diagnostic accuracy of morning salivary cortisol (MSC) concentrations to screen for adrenal suppression in these patients. Forty-eight patients were prospectively randomized to two treatment limbs. Symptom scores and adrenal function assessments were performed immediately prior to commencement and at the end of treatment. One (4 per cent) mometasone furoate and 14 (58 per cent) betamethasone sodium phosphate patients developed biochemical evidence of adrenal suppression. There were statistically significant (p < 0.005) reductions in symptom scores following treatment, but no significant difference (p > 0.05) between the drug groups regarding post-treatment symptom scores. As a screening tool for iatrogenic adrenal suppression, MSC had a sensitivity of 100 per cent and a specificity of 97 per cent. This study demonstrates the high risk of developing adrenal suppression secondary to betamethasone sodium phosphate therapy. The salivary cortisol assay is an accurate tool for monitoring adrenal function and is ideally suited to the out-patient setting.

The relationship between circulating concentrations of C-reactive protein, inflammatory cytokines and cytokine receptors in patients with non-small-cell lung cancer

The relationship between circulating C-reactive protein concentrations and potential cytokine and receptor mediators (interleukin-6, leukaemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF), soluble IL-6 receptor, soluble gp130, soluble TNF receptor, interleukin-1 receptor antagonist and interleukin-8 (IL-8)) of this acute phase protein were examined in healthy subjects (n=11) and patients with non-small-cell lung cancer (n=50). Leukaemia inhibitory factor and CNTF were below detection limits in all controls and patients. C-reactive protein, interleukin-6, soluble gp130, soluble TNF receptor, interleukin-1 receptor antagonist and IL-8 concentrations were significantly elevated in cancer patients (P< or =0.001). Cancer patients with elevated C-reactive protein concentrations had greater concentrations of interleukin-6 (P<0.01) and interleukin-1 receptor antagonist (P<0.05). On regression analysis only interleukin-6 was independently associated with C-reactive protein (r=0.616, P<0.001). Interleukin-6 is an important independent mediator of elevated C-reactive protein concentrations in patients with non-small-cell lung cancer.

Adiponectin and the systemic inflammatory response in weight-losing patients with non-small cell lung cancer

The aim of the present study was to examine the relationship between adiponectin and the systemic inflammatory response in weight-losing patients with non-small cell lung cancer (NSCLC). Measurement of anthropometry, acute phase proteins, interleukin-6, leptin (total and free) and adiponectin were carried out on healthy subjects (n = 13) and non-small cell lung cancer patients with weight loss (n = 20). The groups were age and sex matched. Compared with the controls the cancer group had a lower BMI (p < 0.01), mid-upper arm circumference (p < 0.001), triceps skinfold thickness (p < 0.05) and circulating concentrations of albumin (p < 0.001), haemoglobin (p < 0.05), free and total leptin (p < 0.05) and adiponectin (p < 0.01). In contrast, the cancer group had elevated circulating concentrations of interleukin-6 and C-reactive protein concentrations (p < 0.001). In the cancer group circulating adiponectin concentrations were significantly inversely correlated with both free (rs = -0.675, p = 0.001) and total leptin concentrations (rs = -0.690, p = 0.001). However, neither weight loss, interleukin-6 or C-reactive protein concentrations were correlated with either adiponectin, free or total leptin concentrations in the cancer group. These results suggest that adipokine production is normal and is unlikely to play a major role in the abnormal fat metabolism in weight-losing cancer patients.

The relationship between interleukin-6 and C-reactive protein in patients with benign and malignant prostate disease

The relationship between interleukin-6 and C-reactive protein was evaluated in patients with benign (n=59) and malignant (n=86) prostate disease. The correlation coefficients for patients with benign prostatic disease and prostate cancer were r_s=0.632, P<0.001 and r_s=0.663, P<0.001, respectively. These results indicate that the relationship between interleukin-6 and C-reactive protein is similar in patients with benign and malignant prostate disease.

Comparison of total, complexed and free prostate-specific antigens and their ratios in the detection of prostate cancer in a non-screened population

BACKGROUND

The role of prostate-specific antigen (PSA) isoforms in the detection of prostate cancer in a non-screened population in the UK remains to be determined.

METHODS

Consecutive patients undergoing diagnostic transrectal ultrasound-guided biopsy of the prostate were studied. Prior to biopsy, a blood sample was obtained and total, complexed and free PSA concentrations measured.

RESULTS

Of the 171 patients included in the study, 103 were found to have prostate cancer. There were significant differences in total and complexed PSA concentrations and in the ratio of free-to-total PSA (all P <0.001) between patients with prostate cancer and those with benign disease. Receiver operating characteristics (ROC) curve analysis showed that the corresponding areas under the curves were similar. Restricting the analysis to the 77 patients who had total PSA concentrations between 2 and 10 micro g/L, ROC curve analysis showed that total and complexed PSA concentrations failed to discriminate between benign and malignant disease. In contrast, the areas under the ROC curve were greater for the free-to-total ratio (P = 0.033).

CONCLUSION

These results show that in patients with total PSA concentrations between 2 and 10 micro g/L, the free-to-total PSA ratio was superior to total PSA concentration in discriminating between patients with benign and malignant disease.

Testosterone measurements in early infancy

Circulating testosterone concentrations in infants measured by a direct chemiluminescent immunoassay (Bayer ADVIA Centaur) were compared with those measured by a traditional radioimmunoassay using solvent extraction. The results confirm that neonatal circulating testosterone concentrations are method dependent, and each laboratory should establish method related reference ranges especially if using a direct commercial immunoassay. The results indicate that the Bayer ADVIA Centaur procedure can be used reliably in neonates. Expected values for male and female infants < 10 days old were 2.5-11.1 (n = 36) and 1.7-5.6 (n = 36) nmol/l respectively. For older neonates (10-50 days) the ranges were 0.2-17.2 (n = 42) and 0.1-1.5 (n = 7) nmol/l respectively.

Divergent metabolic and vascular phenotypes in pre-eclampsia and intrauterine growth restriction

OBJECTIVE

Pre-eclampsia (PE) and intrauterine growth restriction (IUGR) may both arise secondary to inadequate trophoblast invasion. Maternal vascular disease is evident only in PE. Little mechanistic evidence exists to explain this dichotomy.

METHODS

We employed laser Doppler imaging (LDI) to examine microvascular function in 15 women with PE and 30 healthy pregnant women matched for body mass index (BMI). We also examined 16 women with IUGR. Other factors examined included indices of inflammation, lipoproteins, leptin and insulin concentrations.

RESULTS

Women with PE had double the concentration of leptin and 30% higher triglyceride than controls. Vascular cell adhesion molecule (VCAM)-1 and interleukin (IL)-6 were also higher in women with PE, with both factors correlating with leptin independently of BMI. No difference in microvascular reactivity was observed between controls and women with PE. Women with IUGR had a four-unit smaller BMI than women with PE. When compared with controls, they also had lower low-density lipoprotein cholesterol (LDL-C) concentrations and systemic inflammatory measures were not elevated.

CONCLUSIONS

The technique of LDI is not sensitive to the vascular dysfunction of PE. However, circulating endothelial-derived factors are elevated in association with markedly elevated leptin levels. Therefore, women with IUGR may demonstrate a protective role for their 'leanness' with regard to maternal systemic inflammatory effect.

Studies on the origin of circulating 18-hydroxycortisol and 18-oxocortisol in normal human subjects

18-Hydroxycortisol (18-OHF) and 18-oxocortisol (18-oxoF) are derivatives of cortisol found in primary aldosteronism but whose origin and regulation in normal subjects are uncertain. 18-OHF can be synthesized by zona fasciculata 11-beta hydroxylase; 18-oxoF can only be produced by zona glomerulosa aldosterone synthase (AS). Stably transfected cell lines expressing either CYP11B1 (11beta-hydroxylase) or CYP11B2 (AS) were incubated with cortisol and other substrates over a range of concentrations. Both enzymes could synthesize 18-OHF from cortisol, but only AS could synthesize 18-oxoF. AS was more efficient than 11beta-hydroxylase at 18-hydroxylation. The apparent Michaelis-Menten constant (K(m)) of AS for cortisol was estimated to be 2.6 microm. In five patients with adrenal insufficiency maintained on hydrocortisone, urinary free cortisol and cortisone levels were high; 18-oxoF was detectable in all patients and 18-OHF in three. It is likely that the 18-oxygenated steroids were synthesized from circulating cortisol, either in the zona glomerulosa or at extraadrenal sites. In eight male volunteers, dexamethasone treatment decreased urinary excretion rates of free cortisol, cortisone, 18-OHF, and 18-oxoF, confirming dependence of 18-oxygenated steroid levels on cortisol availability. In both groups, hydrocortisone administration resulted in detectable levels of 18-OHF and raised levels of 18-oxoF. There was close correlation between 18-oxoF and cortisol excretion during hydrocortisone administration in normal subjects (r = 0.86; P < 0.001). These data show, for the first time, that 18-OHF and 18-oxoF can be synthesized from circulating cortisol. The close correlation between 18-oxoF and cortisol suggests that 18-oxoF is normally produced by the action of AS using circulating cortisol as a substrate. Although 18OHF can be synthesized using circulating cortisol as substrate, our data suggest this is normally produced in the zona fasciculata by 11beta-hydroxylase from locally available cortisol.

Aldosterone synthase gene variation and adrenocortical response to sodium status, angiotensin II and ACTH in normal male subjects

OBJECTIVE

Aldosterone synthase, a key enzyme in the terminal steps of aldosterone synthesis, is encoded by the CYP11B2 gene. A polymorphism in the 5' coding region of this gene (-344 C/T) is associated with hypertension, particularly with elevation of the aldosterone to renin ratio. A second polymorphism (a conversion in intron 2 to resemble that of the neighbouring 11beta-hydroxylase (CYP11B1) gene) is found in close linkage dysequilibrium with the variant at -344 C/T. The mechanism by which these variants predispose to cardiovascular disease and the precise intermediate phenotype associated with them remains speculative.

DESIGN

We performed a focused physiological study in normal volunteers stratified by CYP11B2 genotype.

PATIENTS

Twenty-three subjects homozygous for the T allele and 21 homozygous for the C allele of the -344 C/T polymorphism of CYP11B2 were studied.

MEASUREMENTS

Basal and angiotensin II stimulated plasma and 24-h urinary steroid excretion during low (60 mmol/day) and high (160 mmol/day) sodium intake and plasma steroids after ACTH stimulation were measured.

RESULTS

No influence of polymorphic variation on basal or stimulated plasma cortisol or aldosterone or other plasma steroid concentrations during either dietary phase was seen. However, excretion of tetrahydro-11-deoxycortisol (the urinary metabolite of 11-deoxycortisol), which is the precursor of cortisol) was increased in TT subjects during sodium restriction, consistent with impairment of zona fasciculata 11beta-hydroxylation.

CONCLUSIONS

We conclude that this polymorphism has no major influence on normal zona glomerulosa function but is associated with a change in 11beta-hydroxylation in the zona fasciculata. The mechanism remains uncertain, but alteration of 11-deoxycortisol levels without change in cortisol suggests altered efficiency of 11beta-hydroxylation. In the long term, this may lead to a minor but chronic increase in ACTH drive to the gland, which may have consequences for steroid synthesis and predispose to the risk of cardiovascular disease.

Randomized, crossover comparison study of the short-term effect of oral testosterone undecanoate and intramuscular testosterone depot on linear growth and serum bone alkaline phosphatase

AIM

To compare the effects of oral testosterone undecanoate (TU) 40 mg daily and intramuscular depot sustanon 50 (SUS), 4 weekly, on short-term growth and bone turnover.

METHOD

Prospective, randomised, cross-over study over 26 weeks with 4 weeks of run-in, 8 weeks of treatment I (TU/SUS), 4 weeks of wash-out, 8 weeks of treatment II (SUS/TU) and 4 weeks of final wash-out.

MAIN OUTCOME MEASURES

Weekly change in lower leg length (LLL) as measured by knemometry, i.e. LLL velocity (LLLV) and absolute bone alkaline phosphatase levels (bALP), as well as percentage change in bALP (%bALP).

PATIENTS

Fourteen boys with delayed growth and puberty; two declined and one boy with sickle cell trait dropped out with priapism a week after SUS. The remainder had a median age of 14.3 years (range 12.5-17.4), testicular volume of 2 ml each (2-6), HtSDS of -2.1 (-3.3 to -1.0) and BA delay of 2.4 years (0.7-4.4).

RESULTS

Median LLLV in the treatment blocks was 0.7 mm/wk (-0.27 to 2.2) and LLLV during the run-in and wash-out periods was 0.27 mm/wk (-0.3 to 0.6) (p <0.005). LLLV during treatment with TU and SUS was 0.51 mm/wk (-0.22 to 2.17) and 0.67 mm/wk (-0.27 to 2.2), respectively (NS). Median LLLV during the washout phases that followed the TU block and the SUS block was similar at 0.28 mm/wk (-0.1 to 0.6) and 0.3 mm/wk (-0.2 to 0.6), respectively. LLLV peaks and troughs that were related to the timing of the injection were more evident during SUS therapy. Median bALP during the run-in period was 94.2 U/l (16-282) and the median %bALP during this period was 1.2% (-57, 16). The main rise in bALP occurred during the treatment blocks with a %bALP of 19.3% (-28.8, 121.7) (p <0.005). Median bALP at the beginning and end of the SUS block was 99.7 U/l (51.7, 225) and 170 U/l (64.8, 273), respectively (p <0.05). Median bALP at the beginning and end of the TU block was 111 U/l (51, 287) and 127.6 U/l (66.4, 298) (NS). Median %bALP during SUS was higher than during TU at 28.1% (4.4, 121.7) and 11.8% (-28.8, 83.6) (p = 0.07).

CONCLUSION

At the doses studied, testosterone undecanoate was as effective as sustanon at promoting short-term growth but changes in bone alkaline phosphatase were more marked during sustanon therapy.

Glucocorticoids contribute to the heritability of leptin in Scottish adult female twins

OBJECTIVE

The precise interactions between glucocorticoids and leptin are complex and poorly understood. The aim of the study was to investigate whether the glucocorticoid/leptin interaction is influenced by shared environmental or genetic factors.

DESIGN

We investigated the heritability of body mass index (BMI), circulating leptin and urinary glucocorticoid metabolites [tetrahydrocortisol (THF), alloTHF and tetrahydrocortisone (THE)] in 54 monozygotic (MZ) and 39 dizygotic (DZ) female twins. Analysis was performed using a structural equation modelling package Mx, developed by Neale.

RESULTS

Leptin and BMI showed substantial heritability (68.3% and 71.3%, respectively). Bivariate analysis indicated that the genetic determinants of BMI and leptin are partly shared. Total cortisol metabolites (THF + alloTHF + THE), the (THE + alloTHF)/THE ratio [a marker of 11beta-hydroxysteroid dehydrogenase (11HSD) activity] and the alloTHF/THF ratio (marker for 5alpha-reductase activity) followed an environmental pattern. The heritability of leptin was significantly lowered to 63.8% (P = 0.012) when values were corrected for the influence of total cortisol metabolites but unaffected by markers of 11HSD and 5alpha-reductase activity.

CONCLUSIONS

We confirm that the genetic influence on both BMI and the circulating leptin concentration is substantial and show that these genetic determinants are highly correlated. These genetic factors, which are more likely to be dominant than additive, can be modestly but significantly modified by urinary total cortisol metabolites implying an adrenal influence.

Poor specificity and recovery of urinary free cortisol as determined by the Bayer ADVIA Centaur extraction method

BACKGROUND

Immunoassay methods for urinary free cortisol (UFC) lack specificity, and many procedures have not been fully evaluated for routine use. In the current study we evaluated the Bayer ADVIA Centaur extraction UFC immunoassay and compared results to those obtained by a specific gas chromatography-mass spectrometry (GC-MS) method.

RESULTS

The Bayer ADVIA Centaur cortisol assay lacked specificity. Cortisone, a steroid present in urine at concentrations similar to those of cortisol, demonstrated a cross-reactivity of 44%. In addition, the choice of matrix used to resuspend steroids after solvent extraction from urine affected recovery. Recovery was improved if the recommended urine reconstruction buffer was replaced by steroid-free serum.

CONCLUSION

Irrespective of the sample matrix used, the Centaur method overestimates UFC, giving results up to twice those obtained by a specific GC-MS method.