Comparison of pituitary-thyroid function in patients with endstage renal disease and in age- and sex-matched controls

The Prevalence of Thyroid Abnormalities in Patients With Chronic Kidney Disease: A Cross-Sectional Study at a Tertiary Care Hospital

Background and objective Chronic kidney disease (CKD) is a clinical syndrome characterized by the irreversible loss of kidney function. It is a widespread condition affecting populations worldwide. The kidneys play a crucial role in the metabolism, breakdown, and elimination of thyroid hormone and thyroid-stimulating hormone (TSH). Consequently, thyroid dysfunction can occur as an endocrine manifestation in CKD patients. Previous studies investigating thyroid abnormalities and the severity of CKD have yielded diverse outcomes. In light of this, this study aimed to determine the prevalence of thyroid dysfunction in CKD patients and explore the association between different thyroid dysfunctions and markers of kidney function. Methods A total of 140 CKD patients who met the inclusion criteria were recruited, and their demographic details and routine investigations were recorded. Blood samples were collected for kidney function tests and thyroid function tests. The primary outcome measures included markers of kidney function [urea, creatinine, and estimated glomerular filtration rate (e-GFR)] and thyroid profile [TSH, free thyroxine (FT4), and free triiodothyronine (FT3)]. Mean and standard deviation (SD) were calculated for continuous variables, while frequencies were calculated for categorical data. Fisher's exact test was employed to evaluate the association between two categorical variables, and p-values below 0.05 were considered statistically significant. Results The mean (± SD) urea, creatinine, and e-GFR were found to be 139 (± 81.1) mg/dL, 5.33 (± 4.1) mg/dL, and 20.1 (± 15) ml/min/1.73 m2, respectively. Of note, 133 (95%) patients had elevated urea levels, with the majority (n = 109, 77.8%) having urea levels between 40 and 199 mg/dL; 70 (50%) patients had creatinine levels less than 4 mg/dL, and 107 (76.4%) had e-GFR of less than 30 ml/min/1.73 m2. The mean (± SD) TSH, FT4, and FT3 levels were found to be 6.64 (± 11.2) mIU/ml, 13.6 (± 4.54) pmol/L, and 2.65 (± 1.89) pmol/L, respectively. It was observed that 18 (12.9%, 95% CI: 8.29-19.4%) of the CKD patients had hypothyroidism and 21 (15%, 95% CI: 10.02-21.8%) had subclinical hypothyroidism (SCH), while only two (1.4%, 95% CI: 0.39-5.05%) and five (3.6%, 95% CI: 1.5-8.08%) had hyperthyroidism and subclinical hyperthyroidism, respectively. Thirty-nine (27.9%, 95% CI: 21.1-35.8%) patients had low FT4 levels, whereas a considerable majority (n = 123, 87.9%, 95% CI: 81.41-92.28%) of the patients suffering from CKD were found to have low FT3 levels. The associations of urea levels with SCH, low FT4, and FT3 status were found to be statistically significant with p-values of 0.002, 0.033, and <0.001, respectively. The association between e-GFR and low FT3 status was also statistically significant, with a p-value of 0.014. Conclusion Nine out of 10 patients with CKD were discovered to have low FT3 levels, whereas one in four patients had low FT4 levels. The study participants also exhibited a significant presence of SCH and hypothyroidism, with prevalence rates of 15% and 12.9%, respectively. Urea levels and e-GFR, indicating the severity of CKD, showed a significant association with the presence of various thyroid abnormalities. Hypothyroidism in CKD patients can complicate disease progression, impact mortality rates, and affect overall quality of life. Therefore, routine screening for thyroid abnormalities should be conducted in all CKD patients.

Quantitative characteristics of calcitonin-producing cells in the thyroid and lungs of uremic rats

Uremia leads to a number of metabolic and hormonal disorders induced by renal failure with definite biological and clinical sequels. For this reason and the absence of reports on influence of CRF on calcitonin (CT)-producing cells of the thyroid glands and airways, the author decided to investigate the behavior of neuroendocrine cells in experimental uremia, taking CT-producing cells as an example. The aim of the present study was to examine the number and distribution of CT-producing cells in the thyroid glands and lungs of uremic rats. Fragments of the thyroids and lungs were collected one week after nephrectomy. Paraffin-embedded sections were stained with H+E and by silver impregnation. To identify neuroendocrine cells, immunohistochemical reaction was performed with the use of a specific antibody against calcitonin. It was revealed that the number of CT-immunoreactive cells decrease in the thyroid and considerable increase in the lungs of rats, when compared to the value in the control animals. The results can be regarded as the morphological manifestation of calcitonin-producing endocrine cells in the rat thyroid and lungs to disorders in the internal environment of the body induced by the impairment of renal parenchyma functioning.

Influence of long term erythropoietin therapy on the hypothalamic-pituitary-thyroid axis in patients undergoing capd

OBJECTIVE

Treatment of anemia with recombinant human erythropoietin (rHuEpo) in hemodialysis patients has been associated with improvement of several abnormalities in hypothalamic-pituitary function. The aim of the present study is to investigate the effects of long term erythropoietin therapy on the hypothalamic-pituitary-thyroid hormone axis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).

DESIGN

Single center, prospective study.

PATIENTS AND METHODS

Ten patients who were clinically stable and had been on CAPD were evaluated. Eleven age and sex matched healthy volunteers were chosen as controls. All of the patients were clinically euthyroid. All patients were on CAPD therapy and none of them had received rHuEpo treatment previously. In all patients after basal estimations of free T3, free T4, TSH, GH and prolactin levels, a bolus of 400 microg TRH was administered intravenously. Levels of TSH, GH and prolactin were measured in blood samples collected every 30 min of the 3 h test period. After the treatment with rHuEpo, TRH test with the same protocol was repeated.

RESULTS

Before the improvement in serum hemoglobin levels with rHuEpo treatment, the patients on CAPD showed abnormal hypothalamic-pituitary-thyroidal functions, including delayed and prolonged TSH (NS), paradoxically elevated GH (p < 0.001) and increased and prolonged prolactin (p = 0.001) responses to TRH. After improvement of anemia with rHuEpo no significant difference was found between the patients and control groups for baseline TSH levels. In the patients peak TSH level and AUC of TSH secretion were significantly reduced after the treatment (p < 0.05 for both). Furthermore the improvement in anemia did not eliminate the paradoxic GH and prolonged prolactin responses to TRH administration.

CONCLUSION

Some hypothalamic-pituitary-thyroid function abnormalities including delayed and blunted TSH, increased and prolonged prolactin and paradoxical GH responses to TRH administration were observed in uremic patients treated with CAPD and the improvement in anemia with rHuEpo seems to cause slight changes on the hypothalamic-pituitary-thyroid axis and peripheral thyroid hormones.

Impaired TSH secretion during sustained hyperglucagonemia in anesthetized dogs

We previously demonstrated that hyperglucagonemia may be responsible for thyroid hormone alterations noted in some nonthyroidal illnesses. Since TSH secretion is also known to be altered in many subjects with several nonthyroidal illnesses, we assessed the influence of sustained hyperglucagonemia on TSH secretory pattern in 5 anesthetized dogs. Serum TSH concentrations were determined after a 16-h fast and again at intervals of 15 min during sustained hyperglucagonemia (515-645 pg/mL) induced by iv bolus administration of glucagon 0.1 mg followed by a continuous glucagon infusion 3 ng/kg/min for 3 h. TRH (200 micrograms) was administered iv at 60 min to assess the influence of sustained hyperglucagonemia on the hypothalamic pituitary thyrotroph axis during the study. A control study was also conducted using normal saline instead of glucagon, and both studies were performed in a randomized sequence. Basal TSH levels were not significantly different during both studies. However, serum TSH declined significantly during sustained hyperglucagonemia prior to TRH administration (delta TSH, pre-TRH, -0.86 +/- 0.24 vs 0.02 +/- 0.07 ng/mL for normal saline, p < 0.01). Furthermore, TSH response to iv TRH administration was significantly blunted during glucagon infusion alone as expressed by both the absolute rise (delta TSH, post-TRH, 1.1 +/- 0.5 vs 5.9 +/- 1.7 ng/ml for normal saline, p < 0.01) as well as an integrated response over a 2-h period (sigma TSH, post-TRH, 4.0 +/- 1.1 vs 11.7 +/- 3.5 ng/min/mL, p < 0.001). Therefore, this study demonstrates that sustained hyperglucagonemia inhibits basal TSH secretion as well as TSH response to iv TRH administration, a TSH secretory pattern similar to that noted at the peak of many nonthyroidal illnesses.

Endocrine abnormalities in patients with amyloidosis

This study was conducted to examine systematically the endocrine function in 10 patients diagnosed to have renal amyloidosis. Basal and dynamic endocrine tests (GnRh, TRH, and ACTH stimulation tests as well as modified glucose tolerance test) were performed in all patients. Eight patients had advanced renal disease (creatinine clearance < 10 mL/min). Hypofunction of the thyroid gland was present in 5 out of those 8 patients, and thyroid biopsy confirmed amyloid deposition. Of those 5 patients, pituitary and adrenal defects were present in 2. In conclusion, endocrine abnormalities were evident at a later stage of renal amyloidosis. Hypothyroidism was present in all patients who manifested endocrine defects and should be considered as an early sign of endocrine involvement with the disease.

Evidence of hypothalamic-pituitary thyroid abnormalities in children with end-stage renal disease

Patients with end-stage renal disease may have abnormalities of growth and of gonadal and thyroid hormones, so we attempted to determine the mechanisms that may be involved in the altered thyroid function. We evaluated serum thyroid hormone levels, their changes immediately after hemodialysis, the serum thyrotropin (thyroid-stimulating hormone (TSH) response to thyrotropin releasing hormone, and the circadian pattern of serum TSH in nine children with end-stage renal disease who were between 7 1/2 years and 17 years 1 month of age. Seven patients had been receiving hemodialysis for a median of 3.3 years; the other two were receiving continuous ambulatory peritoneal dialysis. Four patients had low serum total thyroxine (T4) values, and all nine had low free T4 values. Mean concentrations of total T4, free T4, and total triiodothyronine (T3), which were significantly less than normal before hemodialysis, returned to normal levels immediately after dialysis. Postdialysis thyroid hormone increases did not correlate with the decrease in weight or the increase in hematocrit observed immediately after dialysis. All but one patient had basal TSH levels within the normal range. Three patients had a deficient TSH response to thyrotropin releasing hormone, and the TSH response was prolonged in all of them. The mean (+/- SD) nocturnal TSH surge was 50 +/- 68%. Five of the eight patients studied had a nocturnal TSH surge below the normal range (95% confidence limits 47% to 300%). Serum free T4 values correlated with the TSH nocturnal surge (r, 0.73; p less than 0.05). Our findings support the hypothesis that some patients with end-stage renal disease have central hypothyroidism.

Serum thyroglobulin in chronic renal failure--effects of haemodialysis

The influence of chronic renal failure (CRF) on serum thyroglobulin concentration (Tg) was investigated in 37 patients (29 on haemodialysis) and compared with results obtained from matched controls. Serum Tg did not differ significantly between CRF patients not on haemodialysis: median 24.1 micrograms/l, (range 2.5-47.0) and controls: median 23.6 micrograms/l, (range 2.1-53.0). Patients on haemodialysis had a significantly lower serum Tg level: median 11.4 micrograms/l (range 2.1-54.0) compared to controls (p less than 0.01) but no change in serum Tg level could be demonstrated after a single haemodialysis. A possible explanation for the low serum Tg level in patients with CRF on haemodialysis is decreased production parallelling the decreased production rate of T4 and T3. Since CRF patients not on haemodialysis had an unchanged serum Tg level compared to controls, haemodialysis was associated with small changes in serum Tg level, and since none of the patients had a serum Tg value above the upper reference limit we conclude that these changes were not of a magnitude likely to cause misinterpretation of results in routine clinical situations.

Alteration of pituitary-thyroid function in patients with chronic renal failure treated by haemodialysis or continuous ambulatory peritoneal dialysis

Pituitary-thyroid function was investigated in 60 patients with chronic renal failure and 18 normal subjects. Serum triiodothyronine and free thyroxine levels were lower in patients treated by either haemodialysis or continuous ambulatory peritoneal dialysis compared with the normal subjects. Serum thyroxine and free thyroxine index were significantly lower in the haemodialysis-treated patients than in the normal subjects. There were no differences in serum thyroxine and free thyroxine index between the continuous ambulatory peritoneal dialysis-treated and normal groups. Serum thyrotrophin was not raised in any of the groups but the serum thyrotrophin response to thyrotrophin-releasing hormone was blunted in both groups of patients. Basal serum prolactin and growth hormone were raised in both groups of patients but there was no significant difference between them. This study confirmed that pituitary-thyroid function is abnormal in patients receiving haemodialysis and established that a similar pattern of abnormalities occurs in patients undergoing continuous ambulatory peritoneal dialysis.