Hypothyroidism is the second most common endocrine disorder after diabetes and affects individuals of all ages from new born to elderly population. The prevalence of congenital hypothyroidism varies from 1 in 2500 to 1 in 3000 newborns and the prevalence of primary hypothyroidism in adults is around 5-40%. However, the incidence of subclinical thyroid dysfunctions is on rise possibly because of increasing awareness about the disease among masses ,easy and wide spread availability of thyroid hormone assays and possibly universal salt iodization programme.
Ministry of Health and Family Welfare, Government of India has issued the Standard Treatment Guidelines for Hypothyroidism. Following are the major recommendations :
Screening is recommended for the following high risk groups:
- All new born infants
- Pregnant women
- Strong family history of thyroid disorders/or autoimmune disorders
- Having an autoimmune disease like T1DM
- Patients with depression, dyslipidemia and infertility
Primary hypothyroidism constitutes around 95% of the patients with hypothyroidism and in rest 5% it is due to secondary hypothyroidism and drugs. The majority of patients with hypothyroidism are due to Hashimoto’s thyroiditis and postablative therapies particularly 131I radioablation and thyroid surgery in patients with Graves’ disease. Hypothyroidism in few patients is related to thyroiditis and drugs like lithium and amiodarone. Iodine deficiency is a rare cause of hypothyroidism .
The symptoms and signs include weakness (99%), dry coarse skin (76%), slow speech (34%), periorbital puffiness (60%), constipation (40%) and others like pallor and cold skin(48%). Presence of goitre (40%) and delayed deep tendon reflexes (77%) are usual finding on examination.
Diagnosis of primary hypothyroidism is easily established by low T4, low T3 and high TSH (≥10µU/ml). Serum T3 levels are usually normal as increased 5’ monodeiodinase activity and preferential secretion of T3 by the thyroid gland maintains it until the disease advances. Subclinical hypothyroidism is diagnosed by normal T3 and T4 levels and serum TSH is above the reference range. Secondary hypothyroidism is characterized by low T3, T4 and low TSH which may be accompanied with other hormone deficiencies as well.
Management of adult hypothyroidism requires treatment with L-thyroxine which is built-up gradually over a period of weeks from 25 µg and increasing to 100-125 µg daily. The tablet is to be taken in the morning fasting state 45 min, prior to intake of food. The doses may be required to built up more gradual in elderly patients and patients with coronary artery disease. The concurrent administration of iron, calcium and antacids interfere with L-thyroxine absorption and therefore these medications should be administered 6-8h later after L-thyroxine administration. The L-thyroxine replacement is unambiguous in pregnant women with subclinical hypothyroidism (SCH), while in other patient with SCH, presence of goitre, TMA positivity, high LDL-Ch or signs/symptoms related to hypothyroidism warrants L-thyroxine replacement. If there is no benefit in symptoms with L-thyroxine over a period of 3-6 months, then treatment can be withdrawn.
Clinical improvement with therapy with L-thyroxine is marked by dieresis, weight loss, increase in heart rate, appetite and feeling of well being. However, change in voice and improvement in myopathy may take a longer time to recover.
Periodic monitoring of thyroid function is required to assess the adequacy of therapy. The target TSH to be maintained is between 0.5 to 2.5 µU/ml. Initially at 6 weeks and later once in 6 months estimating TSH is usually sufficient to assess the adequacy of replacement therapy.
Guidelines by The Ministry of Health and Family Welfare :
Dr Sailesh Lodha Fortis Escorts Jaipur