Pulsatility of luteinising hormone in men with chronic renal failure: abnormal rather than absent

Androgen deficiency and endothelial dysfunction in men with end-stage kidney disease receiving maintenance hemodialysis

OBJECTIVES AND METHODS

Two thirds of men with end-stage kidney disease (ESKD) have serum testosterone levels in the hypogonadal range. We examined if low serum testosterone levels were correlated with measures of endothelial dysfunction in ESKD. Bilateral common carotid artery (CCA) intima-media thickness (IMT) and atherosclerotic plaque occurrence, left ventricular mass index, flow- (FMD) and nitrate-mediated vasodilatation (NMD) of the brachial artery were determined by ultrasound imaging in 100 nondiabetic men with ESKD (50 men exhibited androgen deficiency; serum testosterone concentrations <300 ng/dl).

RESULTS

Left-ventricular mass index, CCA diameter, CCA-IMT and atherosclerotic plaque occurrence were all significantly increased in ESKD patients with androgen deficiency compared with patients without androgen deficiency (p < 0.05). Also, FMD and NMD measurements were significantly reduced in the former compared with the latter (p < 0.05). Testosterone levels were inversely correlated with age and duration of hemodialysis therapy (r = -0.44 and r = -0.55; p < 0.001). Testosterone levels were negatively correlated to CCA-IMT and atherosclerotic plaque occurrence in patients with androgen deficiency (r = -0.32, p < 0.003, and r = -0.23, p < 0.04, respectively). FMD and NMD measurements were positively correlated to total (r = 0.65 and r = 0.61; both p < 0.0001) and free (r = 0.52 and r = 0.48; both p < 0.001) testosterone levels in patients with low androgenicity.

CONCLUSION

The present results indicated that ESKD patients with androgen deficiency had increased CCA-IMT, atherosclerotic plaque occurrence and reduced FMD and NMD compared with patients without androgen deficiency. Testosterone serum levels were negatively correlated to CCA-IMT and positively correlated to endothelium-dependent vasodilatation in ESKD patients with androgen deficiency.

Circulating inhibitor of gonadotropin releasing hormone secretion by hypothalamic neurons in uremia

BACKGROUND

Previous studies have suggested a neuroendocrine defect underlying uremic hypogonadism, characterized by a reduced secretion of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH).

METHODS

We studied the GnRH-producing GT1-7 cell line and the LH-producing LbetaT-2 pituitary cell line under uremic conditions to investigate whether substances circulating in uremic plasma directly affect hypothalamic or pituitary hormone secretion. The cells were incubated with serum from 5/6-nephrectomized or sham-nephrectomized castrated rats, respectively. Furthermore, GT1 cells were incubated with delipidated sera, serum subfractions separated by molecular weight, or several peptide hormones. Cellular viability, apoptosis rate and extracellular hormone degradation were assessed separately. GnRH and LH were measured by RIA in supernatants and cell lysates. GnRH gene expression was assessed by Northern blot.

RESULTS

Uremic serum caused a reduction of extracellular GnRH concentration by 31%, whereas intracellular GnRH increased by 12%. This effect was independent of serum lipids and enzymatic GnRH degradation but was abolished by trypsin digestion. Cellular viability, apoptosis rates and GnRH gene expression did not differ between the two groups. The inhibitory activity was recovered from the high-molecular weight fraction, whereas the fraction <5 kD had stimulatory activity. In contrast, uremic serum did not affect LH secretion from LbetaT-2 cells, indicating that the hypoactivity of the hypothalamo-pituitary gonadotrope unit results from an inhibition at the hypothalamic rather than the pituitary level.

CONCLUSIONS

Our results suggest that uremic serum contains macromolecular and hydrophilic peptide(s) able to specifically suppress the neurosecretion of GnRH from GT1-7 cells.

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.

Evaluation of the hypothalamic-pituitary axis in uremic males using dynamic tests. The possible role of testicular inhibin: a preliminary report

Two dynamic tests (Gn-RH i.v. and clomiphene citrate-CC p.o.) were used to evaluate the hypothalamic-pituitary axis in hemodialysis patients and renal transplant recipients (recipients). In the Gn-RH test the gonadotropin secretion was maximally decelerated in hemodialysis patients while it was normal in recipients. During the CC test a decrease of gonadotropin secretion, chronically and quantitatively identical for both group, was found; while on the following test days an increase was noted, which was more accelerated in male recipients. In cases with uremia a strong negative feedback dominates at the pituitary level probably owing to testicular inhibin. The estrogenic feedback in uremia was intact, while the antiestrogenic feedback at the level of hypothalamus is partly impaired, owing to altered opioid metabolism.

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

OBJECTIVE

Men with chronic renal failure treated by haemodialysis have raised levels of bioactive LH (B-LH) and immunoreactive LH (I-LH) but reduced B-LH:I-LH (B:I) ratio and testosterone (T) secretion. This study investigated the LH isoform distribution in serum from normal adult males and males on regular haemodialysis treatment.

DESIGN

Four blood samples (2 ml) were obtained at 15-minute intervals from a group of men on regular haemodialysis treatment. These samples were part of a larger pulse profile series and showed no evidence of LH pulsatility. The serum was pooled for each individual patient. Blood (10 ml) was also drawn randomly from healthy male volunteers. The sera were chromatofocused on a 4-ml mono-P column attached to a fast performance liquid chromatography system. This procedure separates the LH isoforms according to their isoelectric point. The pH gradient was between pH 7 and pH 4.

PATIENTS

The five men with chronic renal failure were aged between 18 and 40 years and had been on haemodialysis for a mean of 10 months (5-20). They were sampled the night prior to a dialysis session. The five normal healthy volunteers had never had any endocrine disorder diagnosed.

MEASUREMENTS

An immunoradiometric assay and a commercially available (Delfia) immunofluorimetric assay were employed for detection of LH in the sera and in chromatofocusing fractions. B-LH and testosterone were also measured in the sera.

RESULTS

Hormone data (mean +/- SEM for normal and renal subjects respectively) were 15.5 IU/l +/- 1.2 and 26.9 +/- 7.2 (B-LH), 6.0 IU/l +/- 0.3 and 16.5 +/- 4.8 (irmaLH), 5.7 +/- 0.5 and 13.6 +/- 4.8 (fluorLH), 25.2nmol/l +/- 2.0 and 12.1 +/- 1.2 (T). The serum B:I ratios were 2.6 +/- 0.1 and 2.6 +/- 0.2 (controls, irmaLH and fluorLH respectively) and 1.7 +/- 0.1 and 2.1 +/- 0.1 (chronic renal failure group). Recovery of LH from the column was 111 +/- 12% (mean +/- SEM) by IRMA and 104 +/- 7% by IFMA for the ten FPLC runs. The median pI for the LH distribution measured by both assays was in the region 6.54-6.40 for subjects with chronic renal failure and 6.09-5.95 for controls. Median pI was negatively correlated to the B-LH:irmaLH (P < 0.0001) and B-LH:fluorLH ratios (P = 0.002) in the serum. Furthermore, the proportion of isoforms recovered in the pH region 6.25-5.50 increased with increasing T levels in the serum (P < 0.004).

CONCLUSION

The distribution of LH in serum of men on haemodialysis is more basic than in normal men. The greater the proportion of more acidic LH species, particularly those with a pI of between 5.50-6.25, the higher the ratio of LH bioactivity to immunoactivity and consequently testosterone levels.

Immunoreactive and bioactive luteinizing hormone in pubertal patients with chronic renal failure. Cooperative Study Group on Pubertal Development in Chronic Renal Failure

Disturbed pulsatile LH secretion has been suggested to play a role in the etiology of delayed puberty and disturbed reproductive function in chronic renal failure (CRF), but interpretation of gonadotropin secretion from plasma concentration measurements is confounded by alterations in hormone metabolic clearance. To simultaneously investigate LH secretion and clearance in children, we performed multiple-parameter deconvolution analysis of 11-hour over-night serum LH concentration-time series of bioactive (bio-LH) and immunoreactive (i-LH) hormone in 36 pubertal patients (18 boys) with various degrees of CRF and 10 healthy controls matched for sex and pubertal stage. Twelve patients received conservative treatment for advanced but compensated CRF, 12 were treated by dialysis, and 12 were studied after successful renal transplantation. We observed that: (1) the mean (+/- SE) plasma half-lives of bio-LH and i-LH were increased in the dialysis group (155 +/- 47 and 201 +/- 31 min) and in the patients on conservative treatment (148 +/- 45 and 135 +/- 70 min) compared to controls (59 +/- 28 and 63 +/- 21 min; all P < 0.05). The plasma half-life of bio-LH in patients on conservative treatment or after renal transplantation was inversely correlated with glomerular filtration rate (GFR) (r = -0.70; P < 0.0001). (2) Pulsatile bio-LH production rate was independently affected by pubertal stage (P = 0.018) and treatment status (P = 0.017), increasing across pubertal stages and being significantly lower in dialysis patients (20 +/- 4 IU/liter * 11 hr) and patients on conservative treatment (28 +/- 9) than in controls (43 +/- 9; all P < 0.05). In patients on conservative treatment or after transplantation, a significant positive correlation between pulsatile bio-LH production rate was observed (r = 0.53; P < 0.008). Pulsatile i-LH secretion rate was significantly reduced only in dialysis patients (15 +/- 34 vs. 46 +/- 18; P < 0.05). (3) The reduction of pulsatile i-LH and/or bio-LH production rates was attributable to a halving of the LH mass secreted per burst in patients on conservative (bio-LH: 4.9 +/- 1.9 IU/liter) and dialysis treatment (bio-LH: 3.2 +/- 0.7, i-LH: 2.4 +/- 0.6 IU/liter) versus controls (bio-LH: 6.9 +/- 1.3, i-LH: 5.4 +/- 2.1 IU/liter), whereas the LH pulse frequency was not different between controls and treatment groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Delayed puberty in uremia: pituitary-gonadal function during short-term pulsatile luteinizing hormone-releasing hormone administration

Pubertal development is frequently delayed or disordered in children with chronic renal failure. Both neuroendocrine and peripheral alterations due to uremia have been hypothesized to explain the impairment in the pituitary gonadal axis. The aim of the present study was to evaluate quantitative (immunological) and qualitative (biological) LH secretion, as well as FSH and sex steroids, before and during 7 days of sc LHRH administration (136-150 ng/kg bw every 120 min) in 5 uremic children (13.1-14.8 yr) with delayed puberty. Six nonuremic children (13.2-17.8 yr) with delayed puberty underwent the same schedule and served as control group. On day 0 mean immunoreactive LH (I-LH) levels were higher in uremic (4.5 +/- 0.9 mIU/ml) than in nonuremic (1.9 +/- 03 mIU/ml; p < 0.05) subjects while no differences were observed in bioactive LH (B-LH) levels (2.9 +/- 0.7 mIU/ml vs 2.4 +/- 0.3 mIU/ml). In both groups of subjects testosterone was at prepubertal levels. Spontaneous I-LH and B-LH pulses were observed sporadically in both uremic and nonuremic subjects. Short-term pulsatile LHRH administration induced significant increases in B-LH, I-LH, FSH and testosterone. The B/I LH ratio increased from day 0 (0.7 +/- 0.2) to day 7 (1.3 +/- 0.4; p < 0.05) in uremics while it showed wide fluctuations in nonuremic subjects. On day 7, 4 uremic and 5 nonuremic subjects showed a pulsatile release of B-LH after exogenous LHRH pulses. Our data document that in uremia there are qualitative as well as quantitative abnormalities in pituitary gonadal secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological activity of luteinizing hormone in uraemic children: spontaneous nocturnal secretion and changes after administration of exogenous pulsatile luteinizing hormone-releasing hormone--preliminary observations

Normal pubertal progression is associated with quantitative and qualitative changes in gonadotrophin release. Uraemic children show a delayed or disturbed puberty. We have therefore examined nocturnal gonadotrophin and sex steroid secretion in seven males and three females [age 11-15 years, pubertal stage (PS) 1-3] with chronic renal failure on conservative treatment. In addition to immunoreactive luteinizing hormone (i-LH) we have measured the biological activity of LH (b-LH). Nine children aged 12-17 years with PS 1-3 and normal renal function served as a control group. In two uraemic children, i-LH, b-LH, follicle stimulating hormone and sex steroids were evaluated before and 7 days after pulsatile LH-releasing hormone (LHRH) administration (150 ng/kg body weight subcutaneously every 120 min). Mean i-LH levels were higher in uraemic children than in controls. An increase in i-LH during sleep was found in all controls and in eight of ten uraemic subjects. Mean b-LH levels were lower during sleep and the b/i LH ratio was reduced in uraemic children with PS 2-3 whether asleep or awake compared with controls. Pulsatile administration of LHRH provoked a rise of i-LH and b-LH levels with an increased b/i LH ratio, suggesting an intact pituitary responsiveness. These preliminary data indicate that the gonadotrophin control of LH is abnormal in uraemic children, and that biopotency of LH secretion might be improved after short-term pulsatile LHRH administration.

Pulsatile immunoreactive and bioactive luteinizing hormone secretion in adolescents with chronic renal failure. The Cooperative Study Group on Pubertal Development in Chronic Renal Failure (CSPCRF)

Delayed or arrested pubertal development is common in children with chronic renal failure (CRF). Normal puberty is initiated by the onset of episodic nocturnal secretion of luteinizing hormone (LH) containing an increasing proportion of bioactive hormone. To test the functional integrity of the hypothalamo-pituitary axis in CRF we measured immunoreactive (i-LH) and bioactive (bio-LH) plasma LH concentrations at 15-min intervals from 2000 to 0700 hours in 65 pubertal patients aged 10-23 years [46 boys/19 girls; 20 on conservative treatment (CT), 13 on dialysis (D), 32 with transplants (TP)]. i-LH was determined by radio-immunoassay and bio-LH by a mouse Leydig cell assay. Peak detection was performed by the cluster analysis computer programme. The mean (+/- SD) number of i-LH (in both sexes) and bio-LH pulses (in boys) per profile, and the mean peak area of i-LH (in both sexes) and bio-LH (in girls) were higher in TP than in CT or D patients. The ratio of bio-LH to i-LH increased during puberty in CT (G1 vs G4/5, 0.3 +/- 0.5 vs 1.8 +/- 0.,4) and TP (0.6 +/- 0.7 vs 1.8 +/- 0.7) but remained low in male D patients (0.4 +/- 0.7 vs 1.1 +/- 0.8). The ratios were subnormal, however, even in mature TP patients compared with healthy adults. The bio-LH/i-LH ratio and the bio-LH peak area best predicted integrated nocturnal testosterone concentrations in TP but not in uraemic male patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal changes in severely uncontrolled type 1 (insulin-dependent) diabetes mellitus

To investigate endocrinological changes associated with severely uncontrolled type 1 (insulin-dependent) diabetes mellitus 27 patients (19 men, eight women) with ketoacidosis or severe ketonuria (= group 1) were examined on admission and after recovery. For comparison 13 non-ketotic patients (seven men, six women), admitted for adjustment of treatment because of poor diabetic control (= group 2), and 20 healthy controls were studied. On admission, the serum testosterone levels in men were lower in group 1 (15.1 +/- 2.0 nmol l-1) (mean +/- SEM) than in group 2 (27.2 +/- 2.8 nmol l-1) (p less than 0.01) and healthy controls (20.6 +/- 2.0 nmol l-1) (p less than 0.05). During treatment the testosterone levels in group 1 rapidly rose to the control level. The serum oestradiol levels in women were low in group 1 both on admission and discharge. The serum prolactin levels were low in female patients in group 1 (119 +/- 17 mIU l-1) compared with the women in group 2 (315 +/- 75 mIU l-1) (p less than 0.05). On admission the serum cortisol levels were higher and their response to 1 mg of dexamethasone was weaker in group 1 than in group 2 and healthy controls. After recovery the serum cortisol levels fell by 15% (p less than 0.01) and the response to 1 mg of dexamethasone returned to normal in group 1. In group 1 during treatment the serum free T4 and reverse T3 levels fell, and the T3 levels rose, whereas the thyroid stimulating hormone (TSH) levels and their responses to TRH remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)