| Abstract|| |
This study was undertaken to test the thyroid function in non-dialyzed children with chronic renal failure (CRF). Sixteen children with CRF and 12 healthy children who served as controls were studied for their thyroid function status. We found a significant increase in the serum thyroid stimulating hormone (TSH) level and a significant decrease in serum Triiodo thyronine (T3) levels in children with CRF as compared to the healthy children (p < 0.001). No significant difference was found between children with CRF and healthy children as regards serum thyroxine (T4) and serum free T4 (FT4) (p > 0.2). There was a weak negative correlation between hemoglobin concentration and serum TSH (r = - 45) as well as between blood urea nitrogen and serum T3 (r= -0.30) in children with CRF. These results suggest that children with CRF commonly have a state of biochemical hypothyroidism although they are clinically euthyroid. Early renal transplantation is indicated to correct such metabolic defects.
Keywords: Chronic renal failure, Children, Pre-dialysis, Thyroid function
|How to cite this article:|
El-Hana NA, El Shaikh S, Shaheen FA. Thyroid Function in Children with Chronic Renal Failure. Saudi J Kidney Dis Transpl 1996;7:297-300
|How to cite this URL:|
El-Hana NA, El Shaikh S, Shaheen FA. Thyroid Function in Children with Chronic Renal Failure. Saudi J Kidney Dis Transpl [serial online] 1996 [cited 2020 Sep 28];7:297-300. Available from: http://www.sjkdt.org/text.asp?1996/7/3/297/39493
| Introduction|| |
Thyroid hormones, thyroxine (T4) and triiodo thyronine (T3) play an important role in the maturation and development of the skeleton and affect endochondral calcifycation and the entire process of cartilage growth. In contrast to testosterone and estrogen, the thyroid hormones stimulate the proliferation of cartilage as well as epiphyseal maturation  . The kidney plays a role in the metabolism and clearance of these hormones as well as thyroid-stimulating hormone (TSH) and thyrotropin releasing hormone (TRH). Normally, only trace quantities of iodothyronines, TSHor TRH are excreted in the urine  . Also, kidney tissue processes a thyrozine-5 deiodinase which converts T4 to T3 
Children with CRF share non-specific clinical manifestations seen in hypothyroidism, such as lethargy, poor appetite, constipation, fatigue, yellowish complexion, growth retardation, dry skin and cold intolerance  . In spite of extensive studies, the issue of thyroid function in children with CRF remains inconclusive  . Several factors such as the type of kidney disease e.g., protein-loosing nephropathies; treatment with immunosuppressive drugs for specific renal diseases; the degree and duration of renal failure; the extent of malnutrition; dietary factors, e.g., protein restriction; dialysis, either hemodialysis (HD) with heparin or continuous ambulatory peritoneal dialysis (CAPD);drugs such as anti-hypertensive adrenergic blockers or corticosteroids, and renal transplantation may all influence the results of thyroid function tests  . We tested the thyroid function in non-dialyzed children with CRF as well as healthy controls in order to determine their thyroid status.
| Materials and Methods|| |
The study was performed on 16 children with CRF not yet on dialysis therapy, and 12 healthy children who served as controls. The children with CRF were studied at the time of follow-up in the pediatric nephrology outpatient clinic of the Jeddah Kidney Center (JKC), Saudi Arabia. None of the study children were on anti-hypertensive drugs, corticosteroids or immunosuppressive drugs. Standard laboratory investigations including complete blood count, blood chemistry, ESR and urine and stool analysis were performed on all patients. The thyroid function was studied by measuring serum levels of TSH, T3, T4 and free T4 by ELISA method using the fully automated ES700 system and the reagents were supplied by Boehringer Mannhein Company.
| Results|| |
The study children with CRF were aged between 1.5 and 15 years with a mean age of seven years. There were 10 (62.5%) boys and six (37.5%) girls. The age of the control group ranged between 2.5 and 14 years with a mean of 7.1 years. There were seven (58.3%) boys and five (41.7%) girls in this group. The etiology of CRF in this series was as follows: six (37.5%), chronic glomerulonephritis; four (25%), urinary tract obstruction; three (18.5%), renal hypoplasia; one (6.5%), hemolytic uremic syndrome and two (12.5%), unknown etiology.
The hemoglobin (Hb) concentration in children with CRF ranged between 51-89 gm/L, with a mean value 71 gm/L, while that in the control group ranged between 114 to 132 gm/L with a mean value of 123 gm/L, a difference that was statistically significant. The values of blood urea nitrogen (BUN) and serum creatinine in the children with CRF as well as healthy controls are given in [Table - 1]. As expected, there was a significant increase of these parameters in the children with CRF (P< 0.001).
The serum thyroid hormone profile in the study patients and controls is given in [Table - 2]. The mean serum TSH in children with CRF was 4.36 ± 1.61µU/ml, while in control children it was 2.58 ± 0.57 µU/ml, a difference that was statistically significant (P< 0.001). The mean value of serum T3 in children with CRF was 113.18 ± 17.13 ng/dl, while in the control children, it was 131.56 ± 4.26 ng/dl. Thus, there was a significant decrease in the mean value of serum T3 in children with CRF (p<0.001). The mean serum T4 levels in children with CRF was 6.15 ± 1.52 /ig/dl, while in control children it was 6.33 ± 1.21 fig/dl, a difference that was not statistically significant (p>0.2). The serum free T4 in children with CRF showed a mean value of 1.22 ± 0.15 ng/dl, while in the control children, the mean value was 1.19 ± 0.1 ng/dl. Again, the difference was not statistically significant. (p>0.2).
There was a weak negative correlation between Hb and serum TSH concentration (r= -0.45), but no correlation existed between Hb and serum T3 levels. Also, there was no correlation between BUN of children with CRF and serum TSH while there was a weak negative correlation (r= - 0.30) with serum T3. There was no correlation between serum creatinine and serum T3 of children with CRF.
| Discussion|| |
The present study demonstrates the thyroid function status in children with CRF not yet on dialysis therapy. We noted a state of hypothyroidism in some of these children as evidenced by the significant increase in their serum TSH and decrease in serum T3 levels. Thus, these children were in a state of biochemical hypothyroidism, though clinically euthyroid.
Normal serum TSH levels have been reported in adults  and children , with CRF. Low serum TSH levels have been reported in adults with CRF on prolonged hemodialysis  , but similar data on children are lacking in literature. In our study, there was a significant increase in the mean serum TSH in children with CRF when compared to healthy children, a result that is in accordance with the results of Ijaiya  and Sakurai, et al  . Similar high serum TSH levels have been reported in adults with CRF on conservative management  . The increase in serum TSH in the study children with CRF may be attributed to the increase in half-life of TSH in CRF and/or significant low serum T3 levels seen in these patients.
Our study demonstrated low levels of serum T3 in children with CRF when compared to healthy controls. These results are in agreement with data obtained from Savdie, et al  and Hardy, et al  in children with CRF and Lims, et al  , Sakurai, et al  , and Kayirna et al  in adults with CRF. Lims. et al  mentioned that low serum T3 concentration may confer a protective effect on patients with CRF regarding protein-nitrogen conservation and provide a rationale for not correcting such deficiency. The finding of low serum T3 in children with CRF may be accounted for by the limitation of protein calorie intake due to anorexia in the diseased children, exaggerated catabolism which occurs in uremic patients as well as contribution of protein restriction imposed on most of these patients  . No studies exist reporting increased serum T3 levels in patients with CRF.
Normal serum T4 levels have been reported in adults  and children  with CRF on conservative management. These are similar to our results which demonstrated no significant difference in the serum T4 levels between CRF children and healthy controls. However, low serum T4 levels have been reported in adults with CRF on conservative treatment by Hegedus, et al  , and in children with CRF by Kaptein, et al  . They attributed low serum T4 to the effect of uremic factor which alters binding of T4 to thyroid binding globulin (TBG) or displacement of T4 from TBG  .
Kayima, et al  reported low serum free T4 in adults with CRF on conservative management. Also, Hershman, et al ,,,,,,,, and Hardy, et al  observed low serum free T4 in children with CRF. They attributed this finding to the disturbed peripheral, metabolism of thyroid hormones in patients with CRF. Our study demonstrated normal serum free T4 in children with CRF, which is in accordance with that of Wassner, et al  and Tikanoja, et al  .
In conclusion, our study revealed that biochemical hypothyroidism is commonly seen in children with CRF although they are clinically euthyroid. Thyroid hormone treatment may be indicated only if there is clinical and biochemical evidence of hypothyroidism and only after doing other confirmatory tests. However, caution should be exercised before initiating replacement therapy. Successful renal transplantation leads to normalization of thyroid hormone concentrations in children with CRF  . Hence, early renal transplantation is indicated in such children.
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Nagi Abu El-Hana
Department of Nephrology, Jeddah Kidney center, King Fahd Hospital, Jeddah
[Table - 1], [Table - 2]