Less acidic forms of luteinizing hormone are associated with lower testosterone secretion in men on haemodialysis treatment

Elevated circulating luteinizing hormone levels are associated with diabetic macroalbuminuria in Chinese men and postmenopausal women: A cross-sectional study

BACKGROUND

Associations between sex hormones and diabetic vascular complications have recently been studied, but the role luteinizing hormone (LH) plays in diabetic kidney disease (DKD) remains uncertain. We aimed to investigate the relationship of LH and DKD in Chinese men and postmenopausal women with type 2 diabetes mellitus (T2DM).

METHODS

Data were collected from 1775 T2DM men and postmenopausal women in hospital. The odds ratios (OR) and corresponding 95% confidence intervals (CI) in relation to LH quartiles were obtained by multiple logistic regression analysis.

RESULTS

LH levels were significantly higher in patients with macroalbuminuria than in those with microalbuminuria, but were not higher in patients with microalbuminuria than in those with normoalbuminuria. Consistently, LH in those with an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m² were significantly higher than in those with eGFR≥60 mL/min/1.73m² . The prevalence of macroalbuminuria was obviously increased for subjects of the fourth quartile of LH vs the first to third quartile (20.4% vs 6.2%, 8.0%, 12.2% in men; 25.3% vs 5.5%, 3.8%, 9.3% in postmenopausal women). Multivariate logistic regression demonstrated that subjects within the highest quartile of LH had higher odds of macroalbuminuria than those within the lowest quartile (OR 4.00, 95% CI, 1.87-8.55 for men; OR 9.62, 95% CI, 3.42-27.08 for postmenopausal women), independent of age, diabetes duration, or other metabolic factors. The area under the curve for detecting macroalbuminuria based on LH was 0.662 for men, and 0.767 for postmenopausal women.

CONCLUSION

High LH levels are positively associated with established DKD among Chinese men and postmenopausal women. Elevated LH may be a promising clinical factor for identifying established DKD.

Pubertal development in children with chronic kidney disease

Impairment of pubertal growth and sexual maturation resulting in reduced adult height is an significant complication in children suffering from chronic kidney disease (CKD). Delayed puberty and reduced pubertal growth are most pronounced in children with pre-existing severe stunting before puberty, requiring long-term dialysis treatment, and in transplanted children with poor graft function and high glucocorticoid exposure. In pre-dialysis patients, therapeutic measures to improve pubertal growth are limited and mainly based on the preservation of renal function and the use of growth hormone treatment. In patients with end-stage CKD, early kidney transplantation with steroid withdrawal within 6 months of renal transplantation allows for normal pubertal development in the majority of patients. This review focuses on the underlying pathophysiology and strategies for improving height and development in these patients.

Male Sexual Dysfunction and Chronic Kidney Disease

Male sexual dysfunction is common in chronic kidney disease (CKD), particularly in end-stage renal disease. Historically, this cause of considerable morbidity has been under-reported and under-recognized. The ideal approach to diagnosis and management remains unclear due to a paucity of good quality data, but an understanding of the pathophysiology is necessary in order to address the burden of this important complication of CKD. This paper will review the endocrine dysfunction that occurs in renal disease, particularly the hypothalamic–pituitary–gonadal axis, discuss the causes of erectile dysfunction, infertility, and altered body image and libido in these patients and suggest appropriate treatment interventions.

Prevalence of subnormal testosterone concentrations in men with type 2 diabetes and chronic kidney disease

BACKGROUND

One-third of men with type 2 diabetes have subnormal testosterone concentrations along with inappropriately normal LH and FSH concentrations. It is not known if the presence of renal insufficiency affects free testosterone concentrations in men with type 2 diabetes.

HYPOTHESIS

We hypothesized that type 2 diabetic men with chronic renal disease (CKD; estimated glomerular filtration rate (eGFR) < 60 ml/min per 1.73 m(2)) have lower free testosterone concentrations than men with normal renal function (eGFR ≥ 60 ml/min per 1.73 m(2)).

STUDY DESIGN AND SETTING

This is a retrospective chart review of patients attending diabetes and nephrology clinics. Men with type 2 diabetes who had the following information available were included in the study: testosterone (total and free) done by LC/MS-MS followed by equilibrium dialysis, sex hormone binding globulin, LH, FSH and prolactin concentrations.

PARTICIPANTS

We present data on T and gonadotropin concentrations in 111 men with type 2 diabetes and CKD (stages 3-5) and 182 type 2 diabetic men without CKD.

RESULTS

The prevalence of subnormal free testosterone concentrations was higher in men with type 2 diabetes and CKD as compared to those without CKD (66% vs 37%, P < 0.001). Men with CKD had a higher prevalence of hypergonadotropic hypogonadism (26% vs 5%, P < 0.001) but not of hypogonadotropic hypogonadism (HH; 40% vs 32%, P = 0.22). There was an increase in the prevalence of hypergonadotropic hypogonadism with decreasing eGFR. Fifty-two percent of men with renal failure (CKD stage 5) had hypergonadotropic hypogonadism and 25% had HH. In men with CKD, the hemoglobin concentrations were lower in those with subnormal free T concentrations as compared to men with normal free T concentrations (119 ± 19 vs 128 ± 19 g/l, P = 0.04).

CONCLUSIONS

Two-thirds of men with type 2 diabetes and CKD have subnormal free T concentrations. The hypogonadism associated with CKD is predominantly hypergonadotropic.

Role of testosterone in the pathogenesis, progression, prognosis and comorbidity of men with chronic kidney disease

Testosterone deficiency and hypogonadism are common conditions in men with chronic kidney disease (CKD). A disturbed hypothalamic-pituitary-gonadal axis due to CKD is thought to contribute to androgen deficiency. Data from experimental studies support the hypothesis that exogenous administration of testosterone may induce the activation of the renin-angiotensin system (RAS), the production of endothelin and the regulation of anti- or/and proinflammatory cytokines involved in the pathogenesis of hypertension and kidney damage. On the other hand, low testosterone levels in male patients with CKD are paradoxically associated with a higher risk of morbidity and mortality, possibly explained by anemia, osteoporosis and cardiovascular disease. In this article, we present an overview of clinical and experimental studies of the impact of testosterone on the progression and prognosis of male patients with CKD; even today, this remains a controversial issue.

Growth retardation in children with kidney disease

Growth failure is almost inextricably linked with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Growth failure in CKD has been associated with both increased morbidity and mortality. Growth failure in the setting of kidney disease is multifactorial and is related to poor nutritional status as well as comorbidities, such as anemia, bone and mineral disorders, and alterations in hormonal responses, as well as to aspects of treatment such as steroid exposure. This review covers updated management of growth failure in these children including adequate nutrition, treatment of metabolic alterations, and early administration of recombinant human growth hormone (GH).

Pharmacokinetic factors contribute to the inverse relationship between luteinizing hormone and body mass index in polycystic ovarian syndrome

CONTEXT

Serum LH levels decrease with increasing body mass index (BMI) in women with polycystic ovarian syndrome (PCOS).

OBJECTIVE

The objective of this study was to determine whether pharmacokinetic factors contribute to the effect of obesity on LH in PCOS. PARTICIPANTS/INTERVENTIONS/SETTING: Twenty-one women with PCOS underwent frequent blood sampling, iv administration of GnRH (75 ng/kg), and sc administration of the NAL-GLU GnRH antagonist (150 microg/kg) followed by iv recombinant human LH (rhLH; 300 IU) in the General Clinical Research Center at an academic medical center.

MAIN OUTCOME MEASURES

Pharmacokinetic parameters were estimated by modeling the LH serum concentration profiles after administration of GnRH and rhLH and related to BMI.

RESULTS

Serum levels of LH and rhLH decreased in a distinctly monoexponential fashion in all patients. The apparent biological half-life of rhLH was not influenced by BMI, nor was the total body clearance or apparent volume of distribution. However, the apparent half-life of endogenous LH was inversely related to BMI (r=-0.46; P<0.04), and the estimated total body clearance of endogenous LH was positively related to BMI (r=0.53; P<0.02).

CONCLUSION

Estimated clearance and apparent half-life of endogenous LH are influenced by BMI in women with PCOS, contributing to the inverse relationship between LH and BMI in this population. The absence of an effect of BMI on the pharmacokinetics of rhLH in these subjects suggests that the effect of obesity on clearance of endogenous LH is the result of alterations in the isoform composition of LH secreted by the pituitary.

Therapy Insight: sexual dysfunction in patients with chronic kidney disease

Sexual dysfunction is common in people with chronic kidney disease (CKD). Sexual dysfunction in these patients should be thought of as a multifactorial problem that is affected by a variety of physiological and psychological factors, as well as by comorbid conditions. Assessment of sexual difficulties in patients with CKD, therefore, involves a careful investigation of a variety of domains. The development of treatment strategies presents challenges as it is often difficult to determine the primary factor(s) responsible for the sexual dysfunction. It is important to think of the treatment in the overall context of the management of various medical problems presented by patients with CKD. It must be remembered that the design of therapeutic approaches for each patient is dependent on the systematic evaluation of the functional and psychosocial problems presented, and assessment of the cause(s) of sexual dysfunction.

Restored expression and activity of organic ion transporters rOAT1, rOAT3 and rOCT2 after hyperuricemia in the rat kidney

We previously reported that in hyperuricemic rats, renal impairment occurred and organic ion transport activity decreased, accompanied with a specific decrease in the expression of rat organic anion transporters, rOAT1 and rOAT3, and organic cation transporter, rOCT2. In the present study, we investigated the reversibility of the organic ion transport activity and expression of organic ion transporters (slc22a) during recovery from hyperuricemia. Hyperuricemia was induced by the administration of a chow containing uric acid and oxonic acid, an inhibitor of uric acid metabolism. Four days after discontinuance of the chow, the plasma uric acid concentration returned to the normal level, and renal functions such as creatinine clearance and BUN levels were restored, although the recovery of tubulointerstitial injury was varied in sites of the kidney. Basolateral uptake of p-aminohippurate (PAH) and tetraethylammonium (TEA), and both protein and mRNA levels of rOAT1, rOAT3 and rOCT2 in the kidney gradually improved during 14 days of recovery from hyperuricemia. Basolateral PAH transport showed a higher correlation with the protein level of rOAT1 (r(2)=0.80) than rOAT3 (r(2)=0.34), whereas basolateral TEA transport showed a strong correlation with rOCT2 protein (r(2)=0.91). The plasma testosterone concentration, which is a dominant factor in the regulation of rOCT2, was gradually restored during the recovery from hyperuricemia, but the correlation between the plasma testosterone level and rOCT2 protein expression in the kidney was not significant. These results suggest that the regulation of organic ion transporters, rOAT1, rOAT3 and rOCT2, by hyperuricemia is reversible, and the organic ion transport activity restores according to the expression levels of these transporters.

Clomiphene increases free testosterone levels in men with both secondary hypogonadism and erectile dysfunction: who does and does not benefit?

Secondary hypogonadism is more common than primary gonadal failure and is seen in chronic and acute illnesses. Although testosterone has a role in erections, its importance in erectile dysfunction (ED) has been controversial. Hypogonadism produced by functional suppression of pituitary gonadotropins has been shown to correct with clomiphene citrate, but with a modest effect on sexual function. We wondered if longer treatment would produce improved results. A total of 178 men with secondary hypogonadism and ED received clomiphene citrate for 4 months. Sexual function improved in 75%, with no change in 25%, while significant increases in luteinizing hormone (P<0.001) and free testosterone (P<0.001) occurred in all patients. Multivariable analysis showed that responses decreased significantly with aging (P<0.05). Decreased responses also occurred in men with diabetes, hypertension, coronary artery disease, and multiple medication use. Since these conditions are more prevalent with aging, chronic disease may be a more important determinant of sexual dysfunction. Men with anxiety-related disorders responded better to normalization of testosterone. Assessment of androgen status should be accomplished in all men with ED. For those with lower than normal age-matched levels of testosterone treatment directed at normalizing testosterone with clomiphene citrate is a viable alternative to giving androgen supplements.

Hormonal profile in patients with congestive heart failure

BACKGROUND

Recent progress has been made in the understanding of the cellular and molecular mechanisms of growth hormone action and of its effects on cardiac tissue. The aim of this study was to measure growth hormone concentrations, along with various other hormones, in patients with stable chronic congestive heart failure due to idiopathic dilated cardiomyopathy.

METHODS

The study included 23 ambulatory men, 51.2+/-9.3 years of age, on standard medical therapy for heart failure due to idiopathic dilated cardiomyopathy. All patients underwent clinical and laboratory evaluations, including echocardiogram, radionuclide ventriculography, right heart catheterization, coronary angiography, and right ventricular endomyocardial biopsy. Serum or plasma concentrations of growth, thyroid, sex and adrenal hormones were measured in all patients and compared with those found in 20 age-matched healthy men.

RESULTS

Growth hormone, insulin-like growth factor I, and free testosterone values in patients with idiopathic dilated cardiomyopathy and heart failure were 0.37+/-0.2 ng/ml, 123.7+/-50 ng/ml and 48.6+/-23.8 pmol/l, respectively, versus 0.5+/-0.4 ng/ml (P<0.01), 236.3+/-66.4 ng/ml (P<0.001) and 105+/-17 pmol/l (P<0.01), respectively, in the healthy age-matched individuals. All other hormone concentrations were comparable in both groups.

CONCLUSIONS

Chronic heart failure due to idiopathic dilated cardiomyopathy is associated with a significant decrease in growth hormone, insulin-like growth factor I, and testosterone concentrations, probably due to chronic disease.

Down-regulation of rat organic cation transporter rOCT2 by 5/6 nephrectomy

BACKGROUND

In rat kidneys, the organic ion transporters rOCT1, rOCT2, rOAT1 and rOAT3 are considered to mediate the basolateral uptake of various ionic compounds. However, their changes in chronic renal failure (CRF) are poorly understood. The present study examined the renal handling of organic ions and the expression of these transporters under CRF.

METHODS

5/6 Nephrectomized rats were used as the animal model of CRF. Renal handlings of cimetidine and paraaminohippuric acid (PAH) were examined by in vivo experiments. rOAT1, rOAT3, rOCT1 and rOCT2 expressions were determined by Western blotting.

RESULTS

The tubular secretion rates of both PAH and cimetidine were markedly decreased in CRF rats. Although the distribution rates of PAH into the kidney cortex and medulla, and of cimetidine into the kidney cortex were maintained, the distribution rate of cimetidine into the kidney medulla was significantly decreased in CRF rats. The expression level of the rOCT2 protein was markedly depressed in CRF rats, but those of rOCT1, rOAT1 and rOAT3 were maintained. In addition, the plasma concentration of testosterone, a regulator of rOCT2 expression, was significantly reduced by CRF. Both the renal clearance of cimetidine and rOCT2 expression were recovered by the exogenous administration of testosterone in CRF rats.

CONCLUSIONS

The levels of urinary excretion of cationic drugs, especially substrates for rOCT2, were reduced under CRF partly due to the reduced expression of rOCT2, and the lowered plasma level of testosterone was suggested to be responsible for the depressed rOCT2 expression in CRF.

Endocrine regulation of gonadotropin glycosylation

The pituitary gonadotropins--luteinizing hormone and follicle-stimulating hormone--as well as the placental choriogonadotropin belong to the family of glycoprotein hormones. These structurally related hormones, which regulate several major reproductive functions of the body, are heterodimers consisting of a common alpha-subunit noncovalently bound to a beta-subunit. The N- and O-linked oligosaccharide chains of these gonadotropins play an important role in intracellular folding, assembly, secretion, metabolic clearance, and biological activity of the hormone. Gonadotropin glycosylation is a highly complex process; within the gonadotropes it is modulated by a variety of extrapituitary factors of hypothalamic and gonadal origin. In particular, estrogens and androgens appear to regulate terminal sialylation and/or sulfation of the oligosaccharide attachments and hence some functional properties of the gonadotropin molecule determined by these residues, i.e., metabolic clearance and in vivo biopotency. Through these extrapituitary inputs, the anterior pituitary may not only regulate the quantity but also the quality of the gonadotropin signal delivered to the gonads in a given physiologic or pathologic condition.

Is there any physiological role for gonadotrophin oligosaccharide heterogeneity in humans? I. Gondatrophins are synthesized and released in multiple molecular forms. A matter of fact

Carbohydrates attached to the protein core of all glycoprotein hormones play an essential role in the function of the molecule, influencing a number of intracellular and extracellular processes. As with other members of the glycoprotein hormone family, pituitary gonadotrophins are not produced as single or unique molecules but rather as arrays of isoforms that differ from each other mainly in the structure of their oligosaccharide attachments. In both experimental animals and in humans, the abundance of the different isoforms varies depending on the endocrine status of the donor present at the time of collection of the tissue or sample. Conditions characterized by an oestrogen-enriched hormonal milieu (eg. the preovulatory phase of the menstrual cycle) promote the formation and secretion of variants with relatively low sialic acid and/or sulphate content, whereas physiological deficiency of this sex steroid (as in the postmenopause) favours the production of highly sialylated, long-lived gonadotrophin variants. When tested individually, less sialylated isoforms exhibit higher receptor-binding and in-vitro biological activity but shorter plasma half-life than their more sialylated counterparts. Both the hormonal regulation and the functional differences among the naturally occurring isoforms strongly suggest that gonadotrophin heterogeneity represents a distinctly different mechanism through which the pituitary gland may regulate the intensity and duration of the gonadotrophic stimulus. Nevertheless, whereas the existence of the alternatively glycosylated variants of gonadotrophins in both the pituitary and in serum is currently without doubt, the physiological role of this phenomenon is still a controversial issue and a matter of debate.

Do immunoassays differentially detect different acidity glycoforms of FSH?

OBJECTIVE

The possibility of the carbohydrate residues of glycoproteins affecting their recognition in immunoassays is an important and unresolved issue. This study looked for evidence of differential recognition of FSH glycoform preparations, of variable isoelectric point (pI) and known molarity, using three routine assays employing different antibody configurations.

DESIGN

Seven glycoform preparations with differing pI bands (between 3.8 and 5.5) were produced by isoelectric focusing of recombinant human FSH and the molecular weights determined by mass spectroscopy. Three concentrations of each glycoform were assayed and the results expressed relative to unfractionated material. From the relative responses, recognition differences between the assay methods and between the glycoform preparations were investigated.

MEASUREMENTS

Three routine assays were employed: the commercially available Amerlite(R) enzyme immunoassay and Delfia(R) immunofluorometric assay, together with an in-house competitive two-site radioimmunoassay (RIA).

RESULTS

Overall, the three assays gave the same relative responses for equivalent glycoforms, with the only exceptions involving small differences between some assay pairs for the fractions at the extremes of the pI range investigated. Within each assay type, differences (P < 0.05) of up to 33% existed between glycoforms of different pI, however, these differences showed no patterns or trends across the entire acidity range examined.

CONCLUSIONS

Between the assay methods investigated in this study, few differences exist in the recognition of individual pI bands of FSH when expressed relative to a common unfractionated standard. Differences were apparent in the recognition of the different acidity glycoforms within each assay method, however, these were small and unlikely to be of clinical significance.

Puberty in chronic renal failure

Puberty is a period of transition characterized by a sequence of profound physical and psychological changes leading to full sexual maturity. This process is driven and orchestrated by the awakening of the gonadotropic hormone axis. Chronic renal failure and its treatment may interfere with the onset and progress of puberty by numerous mechanisms including endocrine, metabolic and neuropsychological abnormalities, and drug effects. On average, the onset of puberty is delayed by 2 years in children with chronic renal failure, even after successful transplantation. Moreover, pubertal height gain is only 50% of that observed in healthy children. In this report, we discuss the endocrine mechanisms underlying these alterations and highlight new therapeutical options for pubertal growth failure.

Androgen therapy in chronic renal failure

Chronic renal failure, dialysis and transplantation have major effects on male reproductive health because of the impairment of spermatogenesis, steroidogenesis and sexual function. Hypothalamo-pituitary testicular dysfunction in uraemia is manifest clinically as delayed growth and puberty, sexual dysfunction, androgen deficiency, impaired spermatogenesis and infertility. Apart from renal anaemia, there are at present no proven indications for androgen therapy in chronic renal failure. This chapter reviews the basis and scope for various clinical applications of gonadotropin and androgen therapy as an adjunct to the standard medical care of chronic renal failure. The therapeutic possibilities implied by experimental and clinical findings suggesting that uraemic hypogonadism may be a functional state of gonadotropin deficiency are emphasized.

Differences in serum luteinizing hormone measurements by immunoradiometric assay induced by kinetic manipulation of assay conditions are dependent on the endocrine milieu of serum

Divergent estimates for luteinizing hormone (LH) in individual serum samples may be given by different immunoassays. In order to investigate this phenomenom further, we have studied the effect of differences in assay kinetics within the same immunoradiometric assay (IRMA) configuration on LH measurement in sera from different endocrine states. Three pairs of monoclonal/polyclonal two-site IRMA systems for LH were developed from three LH monoclonal antibodies and a common polyclonal anti-human chorionic gonadotrophin. For IRMA systems a short and long assay, which were different only with respect to the incubation time (1/2 h and overnight respectively), of the labelled monoclonal first antibody were performed. The IRMAs were all standardized against the LH international reference preparation 68/40. LH concentrations were measured by all the IRMAs in sera obtained from normal men (n = 11) and from women with polycystic ovarian syndrome (PCO; n = 13). In normal men, there were no differences in LH estimates between the short and the long assays of the three IRMA systems, and the ratios of long to short assays were similar for all the systems. However, in PCO there were significant differences between short and long assays and the ratios of long to short assays were different for the IRMA systems. These results indicate that kinetic differences between IRMAs of the same antibody configuration can be associated with differences in measured LH concentrations, depending on the endocrine status of the sera studied. As LH glycoform patterns are known to differ between normal men and PCO, the observed changes in LH estimates may be due to the different glycoform composition.

Serum free prostate specific antigen: isoenzymes in benign hyperplasia and cancer of the prostate

Prostate specific antigen (PSA) in serum of patients with benign prostatic hyperplasia (BPH) or prostate cancer (P-CA) not bound to alpha-1-antichymotrypsin (ACT) was analyzed by chromatofocusing. The procedure allowed the simultaneous separation of complexed and free PSA and the fractionation of the free PSA fraction into several isoenzymes. The detection of the isoenzymes was strongly dependent on the combination of antibodies introduced in the applied commercially available immunoassays (Cobas Core, Delfia). Isoenzymes in sera of patients with benign prostatic hyperplasia were mainly situated in the pI range of 6.6 to 7.3. Isoenzymes in sera of prostate cancer patients or in PSA from LNCAP cells were mainly situated in the pI range 7.0 to 8.3. Neuraminidase treatment of the sera shifted the isoelectric points of all three sources towards more basic pHs. An irregular glycosylation process in the dysplastic cells of the prostate is suggested to be the cause for the shift of the isoelectric points. The difference of isoenzyme distribution along the pH axis is discussed as a diagnostic tool to differentiate between BPH and P-CA.