ENDOCRINE EFFECTS OF LITHIUM

Volume 3 Issue 8 August, 2013

Consultation Liaison Psychiatry Focus: Endocrinology

Lithium remains an effective and inexpensive medication to treat Bipolar disorders. Though lithium is among of the best drugs Psychiatrist prescribes in Bipolar disorders, one should be aware of endocrine disorders associated with Lithium.

Hypothyroidism and Goiter

Up to 50% of patients on chronic lithium therapy may develop thyroid enlargement. Generally, it is diffuse, painless, and benign goiter. Up to 30% of patients chronically treated with lithium may develop increased TSH (subclinical hypothyroidism) that may progress to overt hypothyroidism, with or without goiter. Silent thyroiditis and thyrotoxicosis have been less frequently reported. Inhibition of the release of thyroid hormones is the main mechanism involved. It is unclear who may be at risk, generally women, patients with detectable thyroid antibodies prior to initiation of Lithium, longer duration of Lithium use and those living in iodine‐deficient areas. The interval between starting lithium and the onset of goiter may vary from a few weeks to several years. Clinical evaluation of Thyroid abnormalities &Thyroid function test are recommended before starting lithium therapy. It is important to note that the presence of abnormalities in thyroid function is not an contraindication to the use of lithium, neither its discontinuation is required if there is eventual onset of thyroid disturbances during treatment. The management of thyroid dysfunction can be done even with the maintenance of lithium therapy, but the risks and benefits of such approach is to be assessed.

Hyperparathyroidism

Long term use of lithium is generally associated with mild hypercalcemia, which is usually reversible with the withdrawal of the medication. However, in some cases, there may be persistent hypercalcemia, and even the development of hyperparathyroidism, by unknown mechanism. The prevalence of hyperparathyroidism associated with lithium is higher in women (4:1), with the occurrence of both parathyroid adenomas and hyperplasia. A recent review and meta‐analysis about lithium toxicity profile recommends that calcium concentrations should be assessed in suspected patients.

Nephrogenic diabetes insipidus (NDI)

Up to 20% to 40% of patients chronically treated with lithium may develop NDI. Lithium use of is one of the important cause of acquired NDI, which is usually reversible after the withdrawal of the drug. However, in some cases it take long time normalization Thiazide diuretics are a therapeutic option in NDI, but hydrochlorothiazide has the potential to increase lithium toxicity, so it should be used with caution. Amiloride would be a better option because, besides its natriuretic action (causing contraction of extracellular volume, consequent decrease in glomerular filtration, and ultimately leading to decreased urine volume), it also reduces the entry of lithium in distal tubule cells. It is also important to be aware of the possibility of the coexistence of NDI and hypercalcemia related to lithium, since dehydration can exacerbate hypercalcemia.

Other endocrine effects

Weight gain up to 10 kg can occur in almost 30% of patients using lithium, by means of a mechanism that is still unclear. Lithium has also been shown to have insignificant effects on glucose metabolism and hypothalamo‐
pituitary adrenal axis. It is in interest of the patient, that physician / endocrinologist and psychiatrist can mutually
interact & decide, when above said conditions arise.

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