Saudi Journal of Kidney Diseases and Transplantation

LETTER TO THE EDITOR
Year
: 2013  |  Volume : 24  |  Issue : 1  |  Page : 132--134

The impact of thyroid dysfunction on renal function tests


Abdelmula M Abdella1, Botoual Seroj Ekoon1, Gad Allah Modawe2,  
1 Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Alneelain University, Khartoum, Sudan
2 Department of Biochemistry, Faculty of Medicine, Omdurman Islamic University, Omdurman, Sudan

Correspondence Address:
Abdelmula M Abdella
Department of Clinical Chemistry, Faculty of Medical Laboratory Science, Alneelain University, Khartoum
Sudan




How to cite this article:
Abdella AM, Ekoon BS, Modawe GA. The impact of thyroid dysfunction on renal function tests.Saudi J Kidney Dis Transpl 2013;24:132-134


How to cite this URL:
Abdella AM, Ekoon BS, Modawe GA. The impact of thyroid dysfunction on renal function tests. Saudi J Kidney Dis Transpl [serial online] 2013 [cited 2020 Aug 3 ];24:132-134
Available from: http://www.sjkdt.org/text.asp?2013/24/1/132/106310


Full Text

To the Editor,

Thyroid hormones (TH) are necessary for the growth and development of the kidney and for maintenance of water and electrolyte homeostasis. [1] On the other hand, the kidney is involved in the metabolism and elimination of TH. From the clinical view point, both hypothyroidism and hyperthyroidism are accompanied by alterations in the metabolism of water and electrolytes as well as in cardiovascular function. The TH influence water and electrolyte balance in different compartments of the body. [2],[3] Also, it is known that hypothyroidism reduces and hyperthyroidism increases the kidney to body weight ratio by a not fully understood mechanism. [4] The kidney also plays a role in the regulation of metabolism and elimination of TH. [5],[6] This study was conducted to investigate the impact of thyroid dysfunction on serum creatinine and urea levels.

This case-control study included 150 Sudanese patients attending the outpatient clinic at the Khartoum Teaching Hospital, Sudan. They included 75 patients with hypothroidism (69 females and six males, age range 14-72 years) and 75 others with hyperthyroidism (69 females and six males, age range 16-72 years). Additionally, 75 age- and sex-matched healthy subjects (69 females and six males, age range 14-73 years) were studied as controls. All patients with thyroid dysfunction were receiving appropriate treatment. The study was conducted in the period from May 2008 to July 2009. Study data were collected using a structural interviewing questionnnaire.

Blood samples were collected from the case and control subjects and the following tests were performed: blood urea, creatinine and creatinine clearance were determined using a spectrophotometer (Jenaway 302 Biosystem-Jermoney); thyroid stimulating hormone (TSH), thyroxine (T4) and tri-iodo thyronine (T3) were assayed by ELISA. The data were analyzed by a computer program (SPSS) and Student's T-test was used for the calculation. P <0.05 was considered significant.

The questionnaire included age, sex, occupation, duration of the disease and treatment. The duration of the disease in patients with hypo- and hyperthyroidism were 1-22 years and 4 months to 10 years, respectively. The mean (±SD) serum creatinine and urea levels in normal controls were 0.76 ± 0.22 mg/dL and 22.3 ± 6.5 mg/dL, respectively. Among patients with hypothyroidism, the creatinine and urea levels, respectively, were 1.2 ± 0.2 mg/dL and 21.1 ± 6.3 mg/dL and, among patients with hyperthyroidism, the creatinine and urea levels were 0.72 ± 0.2 mg/dL and 23.5 ± 16.7 mg/dL, respectively. There was a statistically significant difference (P <0.05) in serum creatinine levels in patients with hypothyroidism when compared with control subjects. Also, there was a significant decrease in the creatinine clearance (65 ± 4.3 versus 103 ± 6.9 mL/min, P <0.001) and the ratio of serum urea/creatinine (17.5 ± 8.4 versus 29.3 ± 12.9, P = 0.02) in patients with hypothyroidism when compared with the control group. Among patients with hypothyroidism, four months after treatment with levothyroxine, the estimated creatinine clearance rose significantly (65 ± 4.3 versus 91 ± 6.2 mL/min, P <0.001) as shown in [Table 1].{Table 1}

TH influences the function of all body organs and cells. The data presented here clearly indicates how the biochemical markers of renal function may be affected by alteration in the level of TH in the body. This study showed a significant increase in creatinine in patients with hypothyroidism. This change was found to be reversible after thyroxin replacement therapy. Similar changes in serum creatinine levels in patients with hypothyroidism, and improvement with treatment, have been reported in a few scattered studies and case reports. [7],[8] These changes in kidney function tests in humans may be a result of physiological effects, including alterations in renal hemodynamics. [9],[10] In hypothyroidism, there is a reduction in renal blood flow and glomerular filtration rate (GFR) and, hence, reduced clearance of creatinine and urea. [11] Thyroid dysfunction causes significant changes in kidney function; both hypothyroidism and hyperthyroidism affect renal blood flow, GFR, tubular function, electrolyte homeostasis and kidney structure. [12],[13] Hypothyroidism-associated kidney dysfunction seems to be more related directly to a reduction in thyroid hormone levels rather than with thyroid autoimmunity. [14] Hyperthyroidism is characterized by an increase in renal plasma flow and GFR, resulting in a reduction of serum creatinine levels (Syme, 2007). [15] The reduction of serum creatinine has also been reported in sub-clinical hyperthyroidism. [16]

Our study shows that hypothyroidism significantly increases serum creatinine levels and decreases both urea/creatinine ratio and creatinine clearance. The reduced GFR was corrected after treatment of hypothyroidism. Hyperthyroidism decreases serum creatinine levels slightly and increases serum urea.

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