Version July 2025
INTRODUCTION —
This topic review provides an overview of thyroid function and hypothyroidism in chronic kidney disease (CKD). The changes in thyroid hormone metabolism that occur in the nephrotic syndrome and the general issue of thyroid function in nonthyroidal illness are discussed elsewhere. (See "Endocrine dysfunction in the nephrotic syndrome" and "Thyroid function in nonthyroidal illness".)
EPIDEMIOLOGY —
Compared with those who have preserved kidney function, patients with nondialysis chronic kidney disease (CKD) and patients on dialysis have an increased risk of hypothyroidism [1-5], though many cases are subclinical. Prevalence estimates vary according to the definition used, but data from several illustrative studies are as follows:
●In a study of over 460,000 veterans with nondialysis CKD, the prevalence of hypothyroidism, defined as serum thyroid-stimulating hormone (TSH) >5 mU/L or receipt of thyroid supplementation, was approximately 19 percent in those with stage 3 CKD, approximately 25 percent in those with stage 4 CKD, and approximately 26 percent in those with stage 5 CKD [6].
●In a study that included over 2600 patients on maintenance hemodialysis, the prevalence rates of subclinical hypothyroidism, defined as serum TSH between the upper limit of normal and ≤10 mU/L, and overt hypothyroidism, defined as TSH >10 mU/L, were approximately 9 percent and 4 percent, respectively [7].
●Among a cohort of over 1400 patients on peritoneal dialysis, the prevalence of hypothyroidism, defined as serum TSH >5.0 mU/L, was approximately 18 percent [8].
PATHOPHYSIOLOGY —
There appears to be a bidirectional causal link between thyroid dysfunction and kidney disease [3].
Thyroid dysfunction due to kidney disease — All levels of the hypothalamic-pituitary-thyroid axis, including alterations in hormone production, distribution, degradation, and excretion, are affected by impaired kidney function. (See "Thyroid hormone synthesis and physiology".)
Hypothalamic-pituitary dysfunction — In the absence of thyroid disease, the plasma concentration of thyroid-stimulating hormone (TSH) is generally normal in patients with chronic kidney disease (CKD) [4,9,10]. However, the TSH response to exogenous thyrotropin-releasing hormone (TRH) is often blunted and delayed, with a prolonged time required to return to baseline levels [11,12]. Reduced renal clearance may contribute to delayed recovery since TSH and TRH are normally cleared by the kidney. However, the blunted hormone response also suggests disordered function at the hypothalamic-pituitary level that may be induced by uremic toxins. Compared with patients who have normal kidney function, patients with CKD have an attenuated rise in TSH levels during the evening hours [13], and the normally pulsatile secretion of TSH is smaller in amplitude [14].
Despite these perturbations, TSH release responds appropriately to changes in the circulating level of thyroid hormones. Exogenous triiodothyronine (T3) lowers TSH levels [10] and can totally suppress the secretory response to exogenous TRH [11]. On the other hand, TSH production increases appropriately in response to thyroid ablation [15]. The latter response is important clinically since TSH levels should rise (as expected) when a uremic patient develops hypothyroidism [4].
Iodine retention — The kidney normally contributes to the clearance of iodide, primarily by glomerular filtration. Among patients with kidney failure, there is diminished iodide excretion and an increase in plasma inorganic iodide, which results in increased uptake of the iodide by the thyroid gland [16]. Increases in total body inorganic iodide can potentially block thyroid hormone production (the Wolff-Chaikoff effect). Such a change may explain the slightly higher frequency of goiter and hypothyroidism in patients with chronic kidney disease [17].
Hypothyroidism can also result from increased exposure to iodine among patients with kidney failure. As an example, in one study, four children receiving peritoneal dialysis developed iodine overload and hypothyroidism that was attributed to chronic exposure to a povidone-iodine-impregnated gauze from the transfer set [18]. In other studies of patients with advanced CKD or end-stage kidney disease, iodine exposure from contrast media, iodine-rich foods (eg, seaweed), or iodine-rich medications (eg, amiodarone) has been associated with the development of hypothyroidism [19-23].
Nephrotic syndrome — Because over 99 percent of circulating thyroid hormone is protein-bound, patients with heavy protein losses due to nephrotic syndrome may develop thyroid hormone deficiency [24]. It is also possible that heavy protein losses in peritoneal effluent may contribute to thyroid dysfunction in patients on peritoneal dialysis [25]. The relationship between nephrotic syndrome and thyroid function is discussed in detail elsewhere. (See "Endocrine dysfunction in the nephrotic syndrome", section on 'Thyroid function'.)
Medication-induced — Medications may cause hypothyroidism in patients with CKD:
●Roxadustat, a hypoxia-inducible factor prolyl-hydroxylase (HIF-PH) inhibitor used to treat anemia in patients with CKD, has been associated with the development of hypothyroidism [26-28]. The putative mechanism underlaying this association is unclear, but roxadustat may act as a selective agonist of the thyroid hormone receptor [29].
●Amiodarone may confer an increased risk of hypothyroidism in CKD because of its high iodine content. (See 'Iodine retention' above.)
Low T3 levels — Most patients with end-stage kidney disease (ESKD) have decreased plasma levels of free T3 or decreased response to T3. In patients with impaired kidney function, isolated low T3 levels are considered a marker of non-thyroidal illness rather than a manifestation of thyroid pathology or dysfunction. Low T3 and decreased response to T3 are discussed below:
●Diminished conversion of T4 to T3 – In patients with impaired kidney function, decreased plasma levels of T3 typically reflect diminished conversion of T4 (thyroxine) to T3 in the periphery [4,9,30]. This abnormality is not associated with increased conversion of T4 to the metabolically inactive reverse T3 (rT3), since plasma rT3 levels are typically normal. This finding differentiates the patient with CKD from patients with chronic illness [4,30]. In the latter setting, the conversion of T4 to T3 is similarly reduced, but the generation of rT3 from T4 is enhanced.
These changes refer to the total T3 concentration. In contrast, circulating levels of serum T3 sulfate may be increased in patients with ESKD, possibly due to reduced renal clearance [31].
●Other causes of low T3 – Low levels of total T3 also may be due to the following factors:
•Inflammation. Low plasma free T3 levels may also be associated with the malnutrition-inflammation syndrome [32,33]. The latter is a common chronic condition in patients on dialysis associated with markedly increased cytokine levels. (See "Inflammation in patients with kidney function impairment" and "Thyroid function in nonthyroidal illness".)
•Metabolic acidosis [34].
•Reduced protein binding. Circulating thyroid hormones are normally bound to thyroid hormone-binding globulin (TBG) and, to a lesser extent, to prealbumin and albumin. Although circulating TBG and albumin levels are typically normal in patients with CKD (in the absence of the nephrotic syndrome), retained substances due to impaired kidney clearance may inhibit hormone binding to these proteins. As examples, urea, creatinine, indoles, and phenols all strongly inhibit protein binding of T4 [35]. This inhibition may explain why some patients with chronic kidney disease have low serum T4 levels. Another possible contributing factor is that binding inhibitors may inhibit T4 binding to solid-phase matrices such as resin and activated charcoal used in measuring T4 levels [36]. (See "Uremic toxins".)
Free fatty acids and heparin also interfere with T4 binding to TBG. Thus, the routine use of heparin to prevent clotting in the dialysis tubing may explain the transient elevation in serum T4 levels that commonly occurs during hemodialysis [37].
●Decreased response to T3 – Despite the euthyroid status of most uremic patients, there is some evidence for blunted tissue responsiveness of T3 [10]. Although basal oxygen utilization is normal in kidney failure, the expected increase following the administration of T3 is not seen. It has also been suggested that the decreased T3 production may have a protective effect by minimizing protein catabolism [15].
Kidney disease due to thyroid dysfunction — Kidney function may be adversely affected by hypothyroidism via the following mechanisms [3]:
●Changes in glomerular architecture, such as thickened glomerular basement membranes, expanded mesangial matrix, and increased permeability of glomerular capillaries
●Altered renin-angiotensin-aldosterone system activity
●Decreased cardiac output
●Intrarenal vasoconstriction due to reduced synthesis and activity of local vasodilators (eg, nitric oxide and adrenomedullin)
These pathologic changes may underlie in part the association between hypothyroidism and CKD. (See 'Chronic kidney disease' below.)
CLINICAL PRESENTATION AND DIAGNOSIS —
Although substantial clinical overlap exists between chronic kidney disease and hypothyroidism, laboratory tests reliably distinguish between the two conditions.
●Overlapping clinical features – In addition to low total and plasma free triiodothyronine (T3) levels, there are a number of signs and symptoms that are common to both CKD and hypothyroidism, including cold intolerance, puffy appearance, dry skin, lethargy, fatigability, constipation, hair loss, myalgias, anemia, and menorrhagia. Furthermore, the frequency of goiter is increased in end-stage kidney disease [4,38]. Despite these findings, most patients with CKD are considered to be euthyroid, as evidenced by normal plasma concentrations of TSH and free thyroxine (T4) and normal basal metabolic rate and tendon relaxation time [4,9,10,39].
●Establishing the diagnosis – The approach to the evaluation and diagnosis of thyroid disease among patients with chronic kidney disease is the same as that for the general population. (See "Laboratory assessment of thyroid function", section on 'Evaluating for thyroid dysfunction' and "Diagnosis of and screening for hypothyroidism in nonpregnant adults", section on 'Diagnostic evaluation'.)
The diagnosis of hypothyroidism is usually established by the demonstration of an elevated serum TSH concentration in conjunction with a reduced serum-free T4 concentration (algorithm 1) [4]. Delayed deep tendon relaxation may be a confirmatory clinical finding.
THYROID DYSFUNCTION AND OUTCOMES —
Subclinical and overt hypothyroidism are associated with a variety of adverse outcomes in patients with chronic kidney disease (CKD).
Mortality
●Elevated TSH – Multiple studies of patients with CKD have reported associations between elevated thyroid-stimulating hormone (TSH) levels and increased mortality [3]. In a study of over 227,000 veterans with nondialysis CKD, TSH levels >5 mU/L compared with levels ≤5 were associated with a higher risk of mortality (adjusted hazard ratio 1.23) [40]. In another study of over 15,000 veterans new to dialysis, elevated predialysis levels of TSH also were associated with a higher mortality risk [41].
●Low T3/T4 – Low triiodothyronine (T3) concentrations, although initially thought to be an adaptive response to chronic illness, have been associated with all-cause and cardiovascular mortality in patients with CKD [33,42,43]. As an example, in one study of 210 patients on hemodialysis, low T3 concentrations, particularly if persistent throughout the 38-month study, were associated with a higher risk of all-cause and cardiovascular mortality, with hazard ratios of 2.7 and 4.0, respectively [43]. A low thyroxine (T4), but not TSH, was also associated with all-cause and cardiovascular mortality. T3, T4, or TSH did not correlate with noncardiovascular mortality. In another study, lower T3 levels at the initiation of peritoneal dialysis were found to be a predictor of long-term all-cause and cardiovascular mortality, independent of comorbidities and markers of nutrition and inflammation [44]. Whether low T3 and T4 are markers for some other clinical process that associates more directly with mortality or have a causal role remains to be determined, as does the pathophysiologic basis for this association.
Chronic kidney disease — Hypothyroidism may be a risk factor for CKD. Several large studies have reported an association between elevated levels of TSH and a higher risk of incident CKD or CKD progression [45-50]. In one retrospective study of 309 patients with CKD and subclinical hypothyroidism who were followed for approximately 35 months, patients treated with thyroid hormone had a lower annual decline in estimated glomerular filtration rate compared with untreated patients (-2.1 ml/min/1.73m2 versus -5.9 ml/min/1.73m2) [51]. In addition, two patients (1.1 percent) in the treated group developed end-stage kidney disease compared with eight patients (6.2 percent) in the non-treated group. In another observational study, both lower and higher levels of thyroid function (defined by increased and decreased levels of TSH, respectively) were associated with an increased risk of incident kidney dysfunction and progression of CKD [48].
Cardiovascular disease — Hypothyroidism may be an important risk factor for cardiovascular disease in patients with CKD:
●Coronary artery calcification – Thyroid hormone increases expression of several vascular calcification inhibitors [52], and thyroid hormone deficiency is associated with greater coronary artery calcification (CAC) in the CKD population. In a study of 104 patients on maintenance hemodialysis, higher TSH levels were associated with moderately elevated CAC scores [53]. In another study of 84 patients on peritoneal dialysis, low free T3 levels were associated with higher CAC scores. [54].
●Atherosclerosis – In a study of 137 patients on hemodialysis, low free T3 levels were associated with carotid artery atherosclerosis and, in patients without diabetes, increased arterial stiffness [55].
●Heart failure – In a study of 51 patients on peritoneal dialysis, patients with subclinical hypothyroidism had lower left ventricular ejection fraction compared with patients who were euthyroid [56]. In another study of 234 patients on maintenance hemodialysis, low free T3 levels were associated with decreased left ventricular systolic function and increased left ventricular mass [57].
●Endothelial dysfunction – In a study of 99 patients on maintenance hemodialysis, higher TSH levels were associated with worse endothelial function, as assessed by fingertip digital thermal monitoring [58]. In another study of 217 patients with stage 3 and 4 CKD, low free T3 levels were associated with impaired flow-mediated vasodilation [59].
Impaired quality of life — Hypothyroidism may contribute to the impaired quality of life experienced by many patients with CKD. In a two year prospective study of 450 patients on hemodialysis who completed Short-Form 36 surveys and Beck Depression questionnaires every six months, higher levels of TSH were associated with lower health-related quality of life, especially in the domains of energy/fatigue, physical function, and pain [60].
Other sequalae
●Thyroid gland size – Thyroid gland size is often increased in patients with CKD [61]. How this occurs is not clear. Subtle changes in thyroid hormone metabolism observed in many patients with CKD (see 'Thyroid dysfunction due to kidney disease' above) do not appear to be sufficient to produce this alteration. It is possible that kidney failure is associated with the accumulation of an unidentified goitrogen.
●Nodules and carcinoma – Patients with CKD may have a slightly higher frequency of thyroid nodules and thyroid carcinoma [17,62]. Why this might occur is not known.
SUMMARY
●Epidemiology – Patients with nondialysis chronic kidney disease (CKD) and patients on dialysis have an increased risk of hypothyroidism, though many cases are subclinical. (See 'Epidemiology' above.)
●Pathophysiology – There appears to be a bidirectional causal link between thyroid dysfunction and kidney disease. CKD is associated with multiple disturbances in thyroid metabolism that are manifested by low serum-free and total triiodothyronine (T3) levels and normal reverse T3 (rT3) and free thyroxine (T4) concentrations. (See 'Pathophysiology' above.)
●Clinical presentation and diagnosis – There are a number of signs and symptoms that are common to both CKD and hypothyroidism, including cold intolerance, puffy appearance, dry skin, lethargy, fatigability, constipation, hair loss, myalgias, anemia, and menorrhagia. However, most patients with CKD are euthyroid, as evidenced by normal plasma concentrations of thyroid-stimulating hormone TSH and free T4. (See 'Clinical presentation and diagnosis' above.)
●Thyroid dysfunction and outcomes – Among patients with CKD, subclinical and overt hypothyroidism are associated with a variety of adverse outcomes, including increased mortality, CKD progression, cardiovascular disease, and impaired quality of life. (See 'Thyroid dysfunction and outcomes' above.)
ACKNOWLEDGMENT —
The UpToDate editorial staff acknowledges William L Henrich, MD, MACP, who contributed to earlier versions of this topic review.
