Subclinical hypothyroidism treatment

LT4 is indicated for patients with overt hypothyroidism.22 However, the need for treatment is controversial in patients with mild or subclinical disease (TSH less than 10 milli-units/L). There are no large clinical trials that show an outcome benefit with treating these patients, and the therapeutic decision must be individualized.1,23 Many patients with subclinical hypothyroidism do, in fact, have subtle symptoms that improve with LT4 replacement. If the patient s serum cholesterol is elevated,24 or if serum anti-TPOAbs are present, many clinicians recommend LT4 therapy. 

Patients with subclinical hypothyroidism and marked elevations in TSH (greater than 10 miUi-intemational units per liter [mlU/L]) and high titers of TSAb or prior treatment with sodium iodide 131 may benefit from treatment with levothyroxine. 

Kleiner, J., Altshuler, L., Hendrick, V, and Hershman, J.M. (1999) Lithium-induced subclinical hypothyroidism review of the literature and guidelines for treatment. / Clin Psychiatry 60 249-255. 

A common mistake is to treat bipolar depression in the same manner that one treats unipolar depression, overlooking the need for a mood stabilizer. In bipolar depression, the first pharmacological intervention should be to start or optimize treatment with a mood stabilizer rather than to start administering an antidepressant medication. In addition, thyroid function should be evaluated, particularly if the patient is taking lithium. Subclinical hypothyroidism, manifested as an increased thyroid-stimulating hormone level and normal triiodothyronine and thyroxine levels, may present as depression in affectively predisposed individuals. In such cases, the addition of thyroid hormones may be beneficial, even if there is no other evidence of hypothyroidism. 

Lithium Plus Thyroid Supplementation. Treatment-resistant and rapid-cycling bipolar patients may have an increased frequency of thyroid dysfunction. Further, some patients suffer from subclinical hypothyroidism and improve with the addition of thyroid supplementation. In this context, several case reports involving this population found that high doses of the thyroid hormone levothyroxine sodium (T ) were clinically beneficial (122,123 and 124). Kusalic (1.25) found that 6 of 10 rapid cyclers had hypothyroidism, based on their thyrotropin-releasing hormone stimulation tests. Further, the average number of mood episodes per year decreased by more than 75% (i.e., from 9.7 to 2.2) after thyroxine was added to the treatment regimen. 

Patients with beta-thalassemia major have an increased risk of primary hypothyroidism. In 23 patients with beta-thalassemia amiodarone was associated with a high risk of overt hypothyroidism (33 versus 3% in controls) (43). This occurred at up to 3 months after starting amiodarone. The risk of subclinical hypothyroidism was similar in the two groups. In one case overt hypothyroidism resolved spontaneously after withdrawal, but the other patients were given thyroxine. After 21-47 months of treatment three patients developed thyrotoxicosis, with remission after withdrawal. There were no cases of hyperthyroidism in the controls. The authors proposed that patients with beta-thalassemia may be more susceptible to iodine-induced hypothyroidism, related to an underlying defect in iodine in the thyroid, perhaps associated with an effect of iron overload. 

Lithium-induced hypothyroidism has been briefly reviewed (626). Some patients develop more persistent subclinical hypothyroidism (TSH over 5 mU/1, free thyroxine normal) and others overt hypothyroidism (higher risk in women, in those with pre-existing thyroid dysfunction, and those with a family history of hypothyroidism). Since subclinical hypothyroidism is not necessarily asymptomatic, treatment with thyroxine may be necessary in this group (627), as well as in those with more obvious hypothyroidism (628). 

In 1705 patients, aged 65 years or over, who had recently started to take lithium, identified from the 1.3 million adults in Ontario receiving universal health care coverage, the rate of treatment with thyroxine was 5.65 per 100 person-years, significantly higher that the rate of 2.70/100 person-years found in 2406 new users of valproate (629). Of 46 adults taking lithium in a psychiatric clinic, 17% developed overt hypothyroidism while 35% had subclinical hypothyroidism (raised concentrations of thyroid stimulating hormone, TSH) (630). 

Eiris-Punal J, Del Rio-Garma M, Del Rio-Garma MC, Lojo-Rocamonde S, Novo-Rodriguez I, Castro-Gago M. Long-term treatment of children with epilepsy with valproate or carbamazepine may cause subclinical hypothyroidism. Epilepsia 1999 40(12) 1761-6. 

Jaeschke R, Guyatt G, Gerstein H, et al. Does treatment with L-thyroxine influence health status in middle-aged and older adults with subclinical hypothyroidism J Gen Intern Med 1996 11 744-749. 

Levothyroxine treatment Overt or subclinical hypothyroidism Goiter in euthyroid autoimmunthyroiditis... 

Long-term treatment with PVP-I, even at a relatively low dose, can result in thyroid dysfunction. Out of 27 patients in whom PVP-I was applied on the tracheotomy site, the gastrostomy site, the external urethral meatus, or an ulcerated skin for 3-133 months (mean standard deviation 48.0 33.2), subclinical hypothyroidism was seen in 3 patients, mild hyperthyroidism was seen in 1 patient, and subclinical hyperthyroidism was suspected in 7 patients (Nobukuni et al., 1997). Sato et al. (2007) reported two cases of hypothyroidism induced by prolonged habitual gargling with PVP-I for 4 and 10 years, respectively. Shetty and Duthie (1990) and Valayer-Chaleat et al. (1998) reported cases of hyperthyroidism in patients who received topical application of PVP-I for 6 months to treat decubitus ulcers. 

Patients with subclinical hypothyroidism and serum TSH concentrations less than lOmU/1 are not suitable candidates for chronic T4 treatment. 

The systematic treatment of subchnical hypothyroidism remains controversial. In a double-blind, randomized, controlled study of patients with co-existing iron deficiency anemia and subclinical hypothyroidism, a combination of levothyroxine 75 micro-grams/day and oral iron 240 mg/day resulted in increased serum iron, hemoglobin, and serum ferritin concentrations compared with subjects who took oral iron monotherapy. These findings suggest that normalization of serum TSH concentrations may be beneficial if patients with subclinical hypothyroidism are found to have iron deficiency anemia [11 ]. 

Treatment controversy Levotiryroxine monotherapy is tire established standard therapy for overt hypothyroidism or subclinical hypothyroidism witir TSH levels >10 mlU/L (SEDA-31,694). However several groups of patients with hypothyroidism (autoirramme tiryroidectomised, surgically or by radioactive iodine (RAI) those with deiodinase D2 polymorphisms tirose with depression) are symptomatic despite normalisation of TSH with levotiryroxine [15 ]. This extensive review proposes that tirese patients would benefit from combination therapy (levothyroxine and T3). 

Thyroid function and thyroid antibodies were not modified in 20 breast cancer patients (451), and only one case of hypothyroidism with increased thyroid antibodies has been reported (SEDA-20, 337). G-CSF had no effect on thyroid function in 33 patients with cancer, even in patients with pre-existing antibodies (452). Subclinical and spontaneously reversible hyperthyroidism occurred in eight patients without thyroid antibodies and with normal thyroid function before treatment, but this was felt to be related to stressful procedures. 

The occurrence of thyroid dysfunction in 72 patients treated with interferon alfa plus ribavirin (1.0-1.2 g/day) has been compared with that of 75 age- and sex-matched patients treated with interferon alfa alone for chronic hepatitis C (177). Of the former, 42 patients, and of the latter, 40 patients had received previous treatment with interferon alfa alone. There was no difference in the rate of thjroid autoimmunity (antithyroglobuUn, antithjroid peroxidase, and thyroid-stimulating hormone receptor antibodies) between the two groups, but the patients who received interferon alfa plus ribavirin developed subclinical or overt hypothyroidism more often (15 versus 4%). Similarly, the incidence of hypothjroidism increased to 19% in patients who underwent a second treatment with interferon alfa plus ribavirin compared with 4.8% after the first treatment with interferon alfa alone, while the incidence remained essentially the same in patients who had two consecutive treatments with interferon alfa alone... 

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