Recent developments in the management of thyroid disorders are more centered towards minimizing the complications of the established methods of treatment. General considerations during diagnosis and treatment of hypothyroidism and hyperthyroidism are discussed as follows:
Hypothyroidism, due to deficiency of circulating thyroid hormones, is a disease with wide ranging symptoms and signs affecting many systems, hence diagnostic delay in hypothyroidism is common.1,2
This delay, compounded with inadequate therapeutic surveillance is responsible for the poor outcome.1
Usually the symptoms may be atypical and measurement of serum thyroid-stimulating hormone (TSH) levels should be part of biochemical testing for undiagnosed medical conditions. The finding of an elevated serum TSH level should be confirmed by repeated testing and supplemented with measurements of serum levels of thyroxine (T4) and thyroid peroxidase antibodies to verify, quantify and subclassify the abnormality.3
Different assays may give different results hence standardization of the references ranges and units is very essential.1
Analysis of the concentrations of free thyroxine (T4) and TSH in serum is first line tests for hypothyroidism.4
• In primary hypothyroidism, the serum content of T4, T3 is low and that of TSH high
• In central hypothyroidism, the serum content of T4, T3 is low and that of TSH generally low or normal, though slightly increased levels of biologically inactive TSH may also occur
• Subclinical hypothyroidism is characterized by a normal serum level of T4, T3 an increased level of TSH, and the absence of clinical symptoms
When a diagnosis of chronic hypothyroidism is confirmed, treatment with laevothyroxine is started, the initial dose being adjusted to the age and general condition of the patient, and the duration and severity of hypothyroidism. As a rule, full thyroxine replacement therapy should bring the serum TSH level into the normal range. In central hypothyroidism, laevothyroxine treatment is similar, but pituitary function must be evaluated and, if necessary, corticosteroid replacement be instituted before laevothyroxine treatment is started.4
The aim of the treatment should be to render the patient euthyroid.1
Thyroxine therapy should be given if the serum TSH level is higher than 10 mIU/L but for lower TSH values, the decision for therapy should be individualized.5
Diagnosis and treatment can be summarized as below 6
• Symptoms of hypothyroidism are common in other conditions and in normal health. Clinical symptoms and signs are insufficient to make a diagnosis of hypothyroidism, and thyroid function tests are essential
• To diagnose primary hypothyroidism only TSH levels may be measured. Usually a high TSH and low T3 & T4 levels shall be observed. However to diagnose secondary and tertiary hypothyroidism the followng tests may be required: fT3, fT4, Total T3, Total T4. Additionally, 24-hour urine-free T3, antibodies (autoimmune origin), S. cholesterol, anemia, Basal body temperature may be perfomed
• These tests can be affected by non-thyroidal illnesses. In these circumstances, test results return to normal after the illness resolves, and thyroid hormone therapy is not needed and may be harmful
• Different assays may give different results, and there is an initiative to standardise reference ranges and units
• The aim of treatment is to render the patient euthyroid; this is best achieved with levothyroxine alone which is the clinically accepted gold -standard. When adequate levothyroxine is given to lower the TSH to within the reference range, symptoms of hypothyroidism resolve; in some patients fine tuning of TSH within the reference range may be needed
• Patients with ongoing symptoms after appropriate thyroxine treatment should be investigated to diagnose and treat the cause
• The literature on combination of T3+T4 for treatment of hypothyroidism is insufficient regarding any additional benefit over T4 monotherapy. Furthermore large scale clinical trials are required in this segment
• Moreover Treatment with T3 can have adverse effects on bone (for example, osteoporosis) and the heart (for example, arrhythmia)
Treatment of subclinical hypothyroidism
• Subclinical hypothyroidism is defined as a TSH value above the upper limit of the reference range with a free T4 concentration within the reference range. Some patients, especially those with a TSH value greater than 10 mIU/l, may benefit from treatment with levothyroxine
Patients with normal thyroid function tests
• Patients with thyroid function tests within the reference ranges who have continuing symptoms, irrespective of consuming thyroxine, should be investigated for a non-thyroidal cause of their symptoms; an opinion may be sought from an endocrinologist or a physician
- Desai MP. Disorders of thyroid gland in India. Indian J Pediatr. 1997 Jan-Feb;64(1):11-20.
- Jayakumar RV. Hypothyroidism. J Indian Med Assoc. 2006 Oct;104(10):557-60, 562.
- Laurberg P, Andersen S, Bülow Pedersen I, Carlé A. Hypothyroidism in the elderly: pathophysiology, diagnosis and treatment. Drugs Aging. 2005;22(1):23-38.
- Hallengren B. Hypothyroidism--clinical findings, diagnosis, therapy. Thyroid tests should be performed on broad indications. Lakartidningen. 1998 Sep 16;95(38):4091-6.
- Krysiak R, Marek B, Okopien B. Subclinical hypothyroidism. Wiad Lek. 2008;61(4-6):139-45.
- Allahabadia A, Razvi S, Abraham P, Franklyn J. Diagnosis and treatment of primary hypothyroidism. BMJ. 2009 Mar 26;338:b725. doi: 10.1136/bmj.b725.