Subclinical Hypothyroidism

What is Subclinical Hypothyroidism?

The subclinical hypothyroidism can be defined as a medical condition in which the thyroid does not function correctly, the dysfunction being classified as mild. The condition is characterized by normal peripheral thyroid hormone levels, while the thyroid stimulating hormone (TSH) is slightly increased.

According to the specialists in the field, this condition affects approximately 3-8% of the general population. The most important implication is the increased risk of progression to clinical hypothyroidism; studies have shown that 1 in 10 people who are diagnosed with subclinical hypothyroidism is going to be diagnosed with clinical hypothyroidism within a period of three years. This condition is more often encountered in women than men and its prevalence increases as a person ages. Some studies have identified subclinical hypothyroidism as a risk factor for cardiovascular disease but further research is necessary.

Symptoms

Given the fact that the thyroid dysfunction is only mild, there are a lot of people who do not present any symptoms. However, there may be patients experiencing the below-mentioned clinical manifestations:

• The skin is drier than usual
• The cognition is affected, with the thinking process becoming slower
• The memory becomes poorer (both declarative and working memory are impaired)
• The muscles become weaker and the person is easily fatigued (progressive tiredness)
• Increased frequency of muscle cramps
• High sensitivity to cold (patients declare they feel a lot colder than they used to)
• The voice changes, becoming deep and hoarse
• The retention of water is possible, with the puffiness around the eyes becoming visible
• The bowel movements are slowed, with constipation being a frequent complaint
• Mood swings, anxiety and depression can also appear in these patients
• In the cases that are closer to the progression to clinical hypothyroidism, the characteristic goiter can appear
• Patients gain weight
• The hearing might become impaired as well
• Possible risk for cardiovascular disease
• Menorrhagia in women
• Reduced tendon reflexes (most commonly seen in the knee reflex)
• Reduced cardiac rhythm is also possible (bradycardia).

Causes

These are the most common causes that can lead to the appearance of subclinical hypothyroidism:

• Hashimoto’s disease
  • Medical condition that is also known as chronic autoimmune thyroiditis
  • Most often incriminated in the appearance of subclinical hypothyroidism (accounts for 90% of all the cases)
• Hyperthyroidism treatment
  • The changes characteristic of subclinical hypothyroidism appear in particular in patients who have undergone treatment with radioactive iodine, for the overly-functioning thyroid gland
• Surgical intervention or anti-thyroid medication
  • Both account for 5-25% of the patients who are diagnosed with subclinical hypothyroidism
• Medication
  • Lithium
  • Amiodarone
• Surgical intervention at the level of the neck or head (affecting the thyroid as a complication)
• Radiation therapy for different forms of cancer
  • The thyroid gland is quite sensible to radiation therapy and its functioning can be very easily affected by this kind of treatment.

Diagnosis

These are the most common solutions available for the diagnosis of subclinical hypothyroidism:

Blood testing

• TSH hormone levels
  • Repeated measurement should be made due to the circadian fluctuations (the TSH hormone levels are higher at night)
• Serum FT4
  • Confirm that the condition did not yet progress to clinical hypothyroidism
• Thyroid antibody testing
  • Identification of the exact cause of the subclinical hypothyroidism – chronic autoimmune thyroiditis
  • Also recommended in patients who have a goiter, other autoimmune conditions or increased levels of TSH

Ultrasound

• Identification of specific thyroid echo pattern (inhomogeneous)
• This pattern appears before the circulating thyroid antibodies, so it is considered a useful method for the early detection of autoimmune thyroiditis

Aspiration cytology

• Most sensitive method used for the diagnosis of autoimmune thyroiditis
• Last resort, due to the fact that it is considered an invasive method of diagnosis.

Treatment

The patients who would benefit the most from the treatment are the ones who have had high levels of TSH hormone for prolonged periods of time and the blood tests have shown the presence of antithyroid antibodies (increased risk for progression to clinical hypothyroidism). In general, it is considered that treatment should be administered to all patients who have TSH equal or over 10 mIU/L and especially I those who already present some of the clinical features.

In case of pregnant women or those who are planning to conceive, getting treated for this condition is mandatory, so as to reduce the risk of pregnancy complications and prevent the impairment of cognitive functioning in the newborn baby.

In patients who have TSH levels under 10 mIU/L, the doctor will pursue treatment only in those who present specific symptoms, in those who suffer from infertility, have a goiter or antithyroid antibodies identified through the blood testing. The treatment for subclinical hypothyroidism is not indicated in elderly patients who are over 85 years of age.

The standard medication used for the treatment of subclinical hypothyroidism is Levothyroxine. This drug is preferred to other medication, as it has a long half-life (approximately one week) and it offers constant levels of both T3 and T4 in the body, requiring only one single dose per day. The dosage differs according to the age of the patient, being of 50 micrograms for those who are young and of 12.5-25 micrograms for those who are older. In order to establish the correct dosage, the patient will have to be monitored for about six to eight weeks. After that period, the monitoring will be performed every six to twelve weeks.

The main purpose of the medication is to lower and maintain TSH at normal levels (between 1 and 3 mIU/L). Other goals of the treatment include the lowering of bad LDL cholesterol and the improvement of the symptoms experienced by the patients. The contraindications of this treatment include the risk of bone fractures and osteoporosis.

Diet

If you want to improve the symptoms of subclinical hypothyroidism, you will have to eliminate all the refined carbohydrates from your diet. Say goodbye to the products that are made from white flour or to those who contain high quantities of sugar. Instead, search for sources of good carbs, such as the products that are made from or contain whole grains.

You should also eliminate the foods that have a high content of unhealthy, saturated fats. Instead, you should load up on the foods that contains healthy fatty acids, such as fish (salmon, mackerel and sardines), nuts (walnuts) and different types of seeds (flaxseed).

There are certain things that you will have to avoid completely, as they will only increase the TSH levels. These are known as goitrogens and they can do a lot of harm – so, be sure to avoid broccoli, Brussels sprouts, cabbage and kale. You should also eliminate peanuts and soybeans from the diet, for the same purpose as above.

Improve your health by taking dietary supplements, including the following ones: selenium, zinc, vitamin A, vitamin C and vitamins from the B complex (B1, B6, B12 and folic acid).

The Mediterranean style diet is especially recommended for those who are suffering from such health problems. The diet includes plenty of fresh fruits and vegetables, seafood and the extra virgin olive oil that is quite healthy. So, you can definitely consider changing your diet and, soon, you will also see an improvement of your symptoms.