Reversible Renal Insufficiency Attributable to Thyroid Hormone Withdrawal in a Patient With Type 2 Diabetes Mellitus

Acute-on-Chronic Kidney Injury in Thyroid Hormone Withdrawal: A Case with Possible Implications for Radioactive Iodine Planning

The association between renal dysfunction and hypothyroidism is of increasing clinical importance as thyroid hormone replacement may attenuate decline in renal function and improve cardiovascular outcomes in patients with chronic kidney disease (CKD). Although multiple mechanisms for the induction of renal insufficiency in hypothyroidism have been described, the renal impact of short-term, acute hypothyroidism is unknown, which has possible implications for thyroid cancer patients preparing to receive radioactive iodine (RAI). A 56-year-old gentleman with history of unilateral renal agenesis and CKD stage III presented with intermediate-risk papillary thyroid cancer. In preparation for RAI, he underwent thyroid hormone withdrawal (THW) associated with acute kidney injury (AKI), as marked by a decrease in his estimated GFR from 53 to 32 mL/min/1.73 m². Upon resumption of thyroid hormone, renal function returned to baseline within months. Although AKI in this case was not otherwise associated with adverse outcome and reversed upon resumption of thyroid hormone, it is possible that this phenomenon could result in potential harm, particularly in the patient with baseline renal insufficiency. In CKD patients, preparation for RAI therapy may require special consideration; future studies should address the role of recombinant TSH to mitigate deleterious renal effects of acute hypothyroidism in this setting.

Interactions between thyroid disorders and kidney disease

There are several interactions between thyroid and kidney functions in each other organ's disease states. Thyroid hormones affect renal development and physiology. Thyroid hormones have pre-renal and intrinsic renal effects by which they increase the renal blood flow and the glomerular filtration rate (GFR). Hypothyroidism is associated with reduced GFR and hyperthyroidism results in increased GFR as well as increased renin - angiotensin - aldosterone activation. Chronic kidney disease (CKD) is characterized by a low T3 syndrome which is now considered a part of an atypical nonthyroidal illness. CKD patients also have increased incidence of primary hypothyroidism and subclinical hypothyroidism. The physiological benefits of a hypothyroid state in CKD, and the risk of CKD progression with hyperthyroidism emphasize on a conservative approach in the treatment of thyroid hormone abnormalities in CKD. Thyroid dysfunction is also associated with glomerulonephritis often by a common autoimmune etiology. Several drugs could affect both thyroid and kidney functions. There are few described interactions between thyroid and renal malignancies. A detailed knowledge of all these interactions is important for both the nephrologists and endocrinologists for optimal management of the patient.

Age and the thyrotropin response to hypothyroxinemia

CONTEXT

Some studies suggest altered pituitary functioning and TSH production with aging.

OBJECTIVE

Our objective was to test the hypothesis that less TSH production occurs despite comparable hypothyroxinemia with advancing age.

DESIGN

We retrospectively studied adult outpatients of all ages with confirmed hypothyroidism and documented their TSH and free T4 concentrations.

PARTICIPANTS

Two populations of 112 patients were subdivided into four age groups: 1) patients newly diagnosed with primary hypothyroidism and 2) thyroid cancer patients undergoing l-T4 withdrawal in preparation for diagnostic or therapeutic radioiodine.

MAIN OUTCOME MEASURE

The relationship between paired free T-4 and TSH concentrations and patient age was studied.

RESULTS

With spontaneous hypothyroidism, the mean TSH concentration decreased nonsignificantly in each ascending age group with comparable free T4 (FT4) concentrations (<35 yr, 69 mIU/liter; 35-49 yr, 49 mIU/liter; 50-64 yr, 43 mIU/liter; >64 yr, 29 mIU/liter). With iatrogenic hypothyroidism, the mean TSH concentration decreased significantly in each ascending age group (<35 yr, 156 mIU/liter; 35-49 yr, 115 mIU/liter; 50-64 yr, 74 mIU/liter; >64 yr, 46 mIU/liter; P<0.001) despite similar FT4 concentrations. The relationship between the log-transformed TSH and FT4 was significantly and inversely affected by age in multivariate analyses in both spontaneous hypothyroidism (P=0.0005) and in iatrogenic hypothyroidism (P<0.0001).

CONCLUSIONS

Age modifies the pituitary set point or response to comparably reduced free T4 concentrations, resulting in lesser serum TSH elevation in older individuals. This phenomenon occurs with both spontaneous and iatrogenic hypothyroidism. This may be an adaptive response in normal aging or a pathological alteration of pituitary function with age.

Thyroid dysfunction and kidney disease

Thyroid hormones (TH) are essential for an adequate growth and development of the kidney. Conversely, the kidney is not only an organ for metabolism and elimination of TH, but also a target organ of some of the iodothyronines' actions. Thyroid dysfunction causes remarkable changes in glomerular and tubular functions and electrolyte and water homeostasis. Hypothyroidism is accompanied by a decrease in glomerular filtration, hyponatremia, and an alteration of the ability for water excretion. Excessive levels of TH generate an increase in glomerular filtration rate and renal plasma flow. Renal disease, in turn, leads to significant changes in thyroid function. The association of different types of glomerulopathies with both hyper- and hypofunction of the thyroid has been reported. Less frequently, tubulointerstitial disease has been associated with functional thyroid disorders. Nephrotic syndrome is accompanied by changes in the concentrations of TH due primarily to loss of protein in the urine. Acute kidney injury and chronic kidney disease are accompanied by notable effects on the hypothalamus-pituitary-thyroid axis. The secretion of pituitary thyrotropin (TSH) is impaired in uremia. Contrary to other non-thyroidal chronic disease, in uraemic patients it is not unusual to observe the sick euthyroid syndrome with low serum triodothyronine (T(3)) without elevation of reverse T(3) (rT(3)). Some authors have reported associations between thyroid cancer and kidney tumors and each of these organs can develop metastases into the other. Finally, data from recent research suggest that TH, especially T(3), can be considered as a marker for survival in patients with kidney disease.

Lithium toxicity precipitated by profound hypothyroidism

Many patients who have undergone surgical treatment for thyroid cancer are treated with postoperative radioactive iodine ablation. Thyroid hormone is generally stopped for several weeks prior to treatment. We report the case of a woman on long-standing treatment with lithium for bipolar disorder who, after 3 weeks of withdrawal from thyroid hormone, presented to the hospital with severe lithium toxicity. She required admission to the intensive care unit and was treated with hemodialysis and supportive care with resolution of her illness. In this patient, renal dysfunction associated with her hypothyroid state was likely the precipitating event leading to the lithium toxicity. We review the effect of hypothyroidism on renal function and the association of hypothyroidism with drug toxicities. This case illustrates the potential for hypothyroid-induced renal dysfunction to lead to adverse clinical consequences in patients taking medications cleared by the kidneys.