Evaluation of thyroid dysfunction in patients with nephrotic syndrome

Abstract

Background. Thyroid and kidney are interdependent on each other in many ways for optimal functioning of either organs. Proteinuria causes urinary loss of thyroid hormones and thyroid binding globulins in substantial amount resulting in subclinical/overt hypothyroidism. Autoimmunity, which can attack both the organs simultaneously, may also contribute considerably to the abnormal functioning of both organs.
 Aims and objectives. To study the effect of proteinuria on the thyroid function and its association with autoimmunity.
 Methods. The study was carried out on a total number of 60 patients with nephrotic range proteinuria attending the kidney and dialysis clinic PGIMS, Rohtak, India. Thyroid profile and baseline investigations along with Anti-TPO antibodies and renal biopsy were carried out on each patient. Patients were allocated to 2 groups based on Anti TPO antibody results: group A comprising 25 Anti-TPO Ab positive patients and group B comprising 35 Anti-TPO Ab negative patients.
 Results. Group A patients with Anti TPO antibody positivity had more elevated TSH levels (p<0.0001), proteinuria (p=0.0011) and serum creatinine (p=0.0137) as compared to group B patients. Group A patients had more diminished eGFR (p=0.0127) and serum albumin (p=0.0056) than patients in group B. TSH levels were positively correlated with proteinuria r=0.55 (p<0.0001, 95% CI 0.35 to 0.70) and serum creatinine levels r=0.56 (p<0.0001, 95% CI 0.36 to 0.71). TSH levels were negatively correlated with serum albumin levels r=-0.52 (p<0.0001, CI -0.68 to -0.31) and glomerular filtration rate r=-0.54 (p<0.0001, CI -0.69 to -0.33). On histopathology, membranous nephropathy - 29 out of 60 patients, 48% - was the most common finding in both the groups.
 Conclusions. Nephrotic range proteinuria leading to thyroid dysfunction is a common entity but the association with autoimmunity causes an exaggerated effect on both these organs. Our study established a significant correlation between thyroid autoimmunity and nephrotic syndrome. Thus, a high index of suspicion should be kept in all patients with nephrotic syndrome to look for any associated antibodies against thyroid antigens. Autoimmunity causes more proteinuria and more elevations of thyrotropin leading to clinical hypothyroidism; however, the occurrence of overt hypothyroidism necessitating treatment needs further study.

Thyroid Dysfunction and Dysmetabolic Syndrome: The Need for Enhanced Thyrovigilance Strategies

“…TD is common in patients with nephrotic syndrome (NS) [ 51 ]. All patients with nephrotic range proteinuria have increased urinary loss of TH and thyroid-binding globulin [ 52 ]. With a normal thyroid reserve, this causes SHypo; with a low thyroid reserve, this leads to overt hypothyroidism [ 51 ].…”

“…It is essential to recognize and treat this TD with TH replacement. A correlation is also seen between thyroid autoimmunity and NS [ 52 ].…”

“…Resolution of hypothyroidism is associated with significant reduction in serum creatinine levels [ 91 ]. As both hypothyroidism and NS have similar clinical presentations such as facial puffiness, weight gain, and fatigue, TD can be easily missed before it becomes severe enough to cause impairments in other major organs of the body [ 52 ]. If left untreated, it can impair the renal function further.…”

About connection of clinical manifestations of glomerulonephritis with features of the thyroid status of patients

“…Повышенная проницаемость почечного фильтра при ГН, вызывающая повышенную экскрецию белков, в том числе тироксинсвязывающего белка, а также тиреоидных гормонов, ТТГ, казалось бы, должна способствовать снижению их содержания в сыворотке крови. Известны исследования, результаты которых подтверждают связь развития гипотиреоза у пациентов с нефротическим синдромом с повышенной экскрецией с мочой белков и тиреоидных гормонов [19,20]. Между тем в другом крупном когортном исследовании показано, что гипотиреоз ассоциирован не с протеинурией, а с нарушением клубочковой фильтрации [21].…”

“…В частности, Jain D. и соавт. обсуждают возможность иммуноопосредованной сопряженности патологических процессов, происходящих в щитовидной железе и почках при нефротическом синдроме [20]. В своей работе мы затронули лишь одну сторону рассматриваемой проблемы -роль цитокинов в процессах взаимовлияния функционального состояния щитовидной железы и почек при первичном ГН.…”