Study of liver and kidney function tests in patients of hypothyroidism

 

S S Bandebuche¹, S B Jagtap^2*

 

¹Associate Professor, ²Assistant Professor, Department of Biochemistry, Smt. Kashibai Navale Medical College and General Hospital, Narhe, Pune-411041, Maharashtra, INDIA.

Email: santoshdoc007@gmail.com

 

Abstract               Background: In India, thyroid disorders are most common among all endocrine Disorders and hypothyroidism being more common than hyperthyroid state and carcinoma thyroid. Thyroid hormones regulate the basal metabolic rate of all cells, including liver and renal cells and in turn liver and kidney play an important role in thyroid hormones metabolism. So thyroid dysfunction may affect liver and kidney function and liver and kidney diseases may modulate thyroid hormone metabolism. So the present research was aimed to study the liver and kidney function tests in patients of hypothyroidism. Material and Methods: Thyroid hormones were measured by Minividas immunoanalyser. Biochemical parameters of liver and kidney function tests were estimated by kit method using Erba EM360 autoanalyser while serum electrolytes were estimated by ion selective electrodes. Results: Significant rise in biochemical parameters of LFT (ALT, AST) and biochemical parameters of KFT(Urea, creatinine, potassium) and significant decrease in sodium and chloride were observed in hypothyroid subjects (TSH >10 mIU/ml ) as compared to euthyroid subjects. Conclusion: Hyypothyroid patients should be regularly checked for biochemical parameters of LFT and KFT as early detection and treatment can prevent the further complications related to the disorder and will be helpful during the management of thyroid patients.

Key Words: Hypothyroidism, kidney and liver function tests.

 

 

 

INTRODUCTION

In India, thyroid disorders are most common among all endocrine disorders and hypothyroidism being more common than hyperthyroid state and carcinoma thyroid.¹ Hypothyroidism is the disease state caused by insufficient production of thyroid hormones by the thyroid gland. These thyroid hormones (T4 and T3) regulate the rate of metabolism, affect growth, and modulate energy utilization by increasing the basal metabolic rate and increasing oxygen consumption, and facilitating heat production² Thyroid hormones regulate the basal metabolic rate of all cells including hepatocytes, and hence, modulate hepatic function; the liver in turn metabolizes the thyroid hormones and regulates their systemic endocrine effects³. Normal circulating levels of thyroid hormone are required for both normal hepatic circulation and normal bilirubin metabolism⁴. Thyroid dysfunction may perturb liver function and vice-versa³. The interplay between kidney and thyroid in each other’s functions is also known for many years. Thyroid hormones are essential for the normal growth and development of the kidney, for the maintenance of water and electrolyte homeostasis. On the other hand, kidney is involved in the metabolism and elimination of thyroid hormone, also a target organ of some of the iodothyronine’s action especially T3.^5,6 Knowledge of the association between hypothyroidism and deranged biochemical markers of liver function and kidney function is important for the clinician to consider an evaluation of thyroid function in the work up of the patient with altered liver and kidney function tests. This may emphasize the need for monitoring liver and kidney function in hypothyroid patients. Therefore the present study was undertaken to assess the changes in liver and kidney function tests in hypothyroid subjects.

 

MATERIAL AND METHODS

Institutional ethical committee clearance was obtained for the present cross –sectional study which was conducted on 90 ambulatory subjects of age group 18 to 55 years, mainly the referral cases from different outpatient departments of the hospital presenting first time for thyroid testing. Patients of hypothyroidism based on laboratory diagnosis were included as cases while age and sex matched, healthy euthyroid subjects formed control group. Patients with intake of thyroid drugs, pregnancy, age group <18 yrs and >60 yrs., diabetes mellitus, hypertension, renal disorders and liver disorders were excluded from the study. About 3 ml of fasting, venous blood sample was collected after written informed consent with all aseptic precautions in plain bulb for estimations of thyroid hormones (Total T3, Total T4 and TSH) and biochemical parameters of liver(serum bilirubin, ALT, AST, ALP, serum total protein and albumin) and kidney (serum urea, creatinine and serum electrolytes) function tests. LFT and KFT parameters were analysed on Erba EM360 autoanalyser. Serum electrolytes were estimated by ion selective electrodes. Thyroid hormones were estimated by Minividas immunoassay analyser. The normal reference range of liver profile according to the kits are Total bilirubin: 0.2-1.3 mg/dl, AST: up to 45 IU/L,ALT: up to 45 IU/L, ALP: 53-128 IU/L, Total protein : 6.0-8.3 gm/dl and Albumin: 3.5-5.2 gm/dl. The normal reference range of kidney profile according to the kits are, Urea- 15-40mg/dl. Creatinine: 0.6-1.2 mg/dl, Sodium : 135-145 mmol/L, Potassium : 3.5-5.5 mmol/L and Chloride : 96-106 mmol/L. The normal reference range of thyroid profile according to the kits are TSH 0.25- 5.00 μ IU/ml, T3 0.55–1.60ng/ml, T4 4.66 – 9.33μg/dl.

Statistical Analysis: The variables were presented in terms of mean and standard deviation. The data were analyzed using student’s unpaired ‘t’ test ‘p’ values <0.001 were considered significant.

 

OBSERVATION AND RESULTS

The study comprised of 60 newly diagnosed hypothyroid cases and 30 age and sex matched healthy controls. Mean age of hypothyroid subjects was 46.38±4.81 years and that of euthyroid subjects was 45.45±4.46 years. Hypothyroid group consisted of 73 % women whereas euthyroid group had 70 % women.

 

Table 1: Thyroid hormones levels in controls and cases

 

Table 2: Comparison of LFT analytes between controls, group I hypothyroid and group II hypothyroid

Tests	Controls/euthyroid (TSH: between 0.25 -5 mIU/ml)	Hypothyroid group I (TSH: between 5 -10 mIU/ml)	P value	Hypothyroid group III (TSH: > 10 mIU/ml)	P vlaue
Total Bilirubin (mg/dl)	0.40±0.10	0.42±0.13	0.506	0.45±0.24	0.296
AST (IU/L)	18.56±3.78	20±4.66	0.193	30.46±3.80	<0.001
ALT(IU/L)	23.16±4.66	24..9±5.04	0.149	47.2±3.44	<0.001
ALP(IU/L)	58.33±12.77	54±11.77	0.177	56.10±14.41	0.528
Total Proteins(g/dl)	6.63±0.2	6.56±0.27	0.255	6.47±0.22	0.108
Albumin(g/dl)	3.7±0.07	3.6±0.27	0.05	3.65±0.24	0.23

 

Table 3: Comparison of RFT analytes between controls, group I hypothyroid and group II hypothyroid

 DISCUSSION

A highly significant difference was observed in serum TSH, T4 and T3 between the study group and the control group. Hypothyroid patients were divided into two groups depending on TSH level as, group I hypothyroid (TSH: between 5 -10 mIU/ml), group II hypothyroid (TSH: between >10 mIU/ml) for statistical evaluation. There was no significant difference in serum total bilirubin, ALP, total proteins and albumin levels between euthyroid, group I hypothyroid and group II hypothyroid. But significant difference was observed in AST and ALT levels in group II hypothyroid as compared to control group. Aspartate and Alanine transaminases elevation may be attributed to myopathies which are usually associated with hypothyroidism.⁴ The levels of serum urea in hypothyroid subjects were within normal range (<40 mg/dl) but significantly higher in group II hypothyroid than euthyroid subjects. Present study correlated well with studies done by Vaneet Kaur et al.⁷, Vandana Saini et al.⁸ and G.K. Sidhu et al.⁹ which also showed that mean serum urea level was significantly higher in comparison to euthyroid controls. However not in agreement with studies by Q. A. Rashead et al.¹⁰ The levels of serum creatinine in hypothyroid subjects were within normal range (<1.3mg/dl) but significantly higher in group II hypothyroid than euthyroid subjects. Studies by Kreisman and Hennessey et al.¹¹, Khan AH et al¹². and Vaneet Kaur et al⁷ and G.K. Sidhu et al.⁹ also point toward mean serum creatinine level being significantly higher in hypothyroid cases. Long standing hypothyroidism can cause significant changes in renal function such as a decrease in sodium reabsorption in the proximal tubule, impairment in the concentrating and diluting capacities of the distal tubules, a decrease in the urinary urate excretion and a decrease in the renal blood flow and glomerular filtration rate (GFR).^13,14 The deficiency of thyroid hormones reduces the cardiac output leading to generalized hypodynamic state of the circulatory system.¹⁵ may increase serum urea and creatinine level. Serum creatinine level may also be increased due to hypothyroid myopathy.¹² There was significant decrease in the serum levels of sodium and chloride and significant increase in potassium levels in group II hypothyroid patients as compared to controls. Plasma Renin Activity (PRA) and Plasma Aldosterone (PA) may be suppressed in hypothyroidism probably due to dysfunction of juxtaglomerular cells and glomerulosa cells respectively and the possibility that suppression of PRA and PA in patients with hypothyroidism is related to exaggerated sodium excretion and decrease in potassium excretion cannot be ruled out.¹⁶ Hypothyroidism may be associated with deteriorating liver and renal function. The understanding of this association can prevent unnecessary investigations, treatment cost and worry in patients presenting with either increased transaminases, urea, or creatinine with undetermined thyroid status. The thyroid function should, therefore, be regularly monitored for evaluation of patients presenting with deranged liver and renal function and vice versa.

 

CONCLUSION

Findings of the present study are helpful in understanding the complex interactions between the thyroid gland and major organ systems like liver and kidney. This suggest that hypothyroid patients should be regularly checked for biochemical parameters of liver and kidney function tests. Early detection and treatment can prevent the further complications related to the disorder and will be helpful during the management of thyroid patients A multisystem approach should be taken to evaluate and treat patients with hypothyroidism to avoid missing subtle but clinically relevant abnormalties.

 

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