What Is Central Hypothyroidism?

Central hypothyroidism (CeH) is a rare disorder characterized by deficient thyroid hormone production caused by abnormal function of the pituitary gland, hypothalamus, or both. 

The hypothalamus and pituitary gland are at the center of thyroid hormone control. The hypothalamus releases ​​thyrotropin-releasing hormone (TRH), which triggers the pituitary gland to release thyroid-stimulating hormone (TSH). TSH then stimulates the thyroid to produce and release two major hormones: Thyroxine (T4) and triiodothyronine (T3) into the bloodstream.

Thyroid hormones play an important role in virtually every aspect of your health, including metabolism, heart rate, energy expenditure, body temperature, skin, hair, and nail growth.

The three endocrine glands, known as the hypothalamic-pituitary-thyroid axis, work together on a feedback loop to keep thyroid hormone production within a normal range. If the hypothalamus and/or pituitary gland are dysfunctional or damaged, an otherwise healthy thyroid will produce insufficient thyroid hormone levels.

This article explores central hypothyroidism symptoms, causes, diagnosis, and treatments. 

Central Hypothyroidism Symptoms

Central hypothyroidism symptoms vary from person to person, depending on the severity of thyroid hormone deficiency. Common symptoms of central hypothyroidism include:

• Cold intolerance 
• Cognitive impairment/memory problems
• Decreased libido (sex drive) 
• Fatigue
• Hair loss
• Hoarseness
• Menstrual problems
• Pale, dry skin 
• Recurrent headaches
• Visual field disturbances (e.g., blind spots, trouble seeing out of the corner of the eye)
• Weight gain

Causes

Central hypothyroidism may be congenital (present at birth) or acquired in childhood or adulthood due to hypothalamic or pituitary disease or injury.

Causes of central hypothyroidism include:

• Genetic mutations 
• Pituitary tumor 
• Hypothalamic lesions 
• Chemotherapy drugs 
• Head trauma
• Radiation therapy
• Sheehan syndrome (a rare condition that may develop from excessive bleeding during childbirth)
• Infections (e.g., tuberculosis) 

Diagnosis

To diagnose central hypothyroidism, your healthcare provider will ask about your medical history and perform a physical examination to check your vital signs, including your body temperature, heart rate, and reflexes. They may palpate (feel) your neck to check your thyroid gland's size, location, and texture.

Important information to tell your healthcare provider includes:

• Symptoms you are experiencing that may be related to hypothyroidism 
• Your personal history of thyroid surgery and/or radiation to the neck 
• Past and current medications you are taking, as some medications may cause hypothyroidism 
• Your family history of thyroid disease

Blood tests are the best way to accurately diagnose central hypothyroidism. Thyroid blood tests include:

• Free T4: Measures thyroxine (T4) levels
• Total T3 levels: Measures triiodothyronine (T3) levels
• Serum TSH: Measures thyroid-stimulating hormone levels
• Thyroid antibody tests: Measure the level of thyroid antibodies to help identify the cause of hypothyroidism (e.g., autoimmune disorders)
• Alpha subunit (proteins) and/or prolactin (a pituitary gland hormone) level tests

Low TSH levels are often associated with primary hyperthyroidism, whereas low T4 with low-to-normal TSH levels are hallmark indicators of central hypothyroidism.

Your healthcare provider may order imaging tests, such as a magnetic resonance imaging MRI of the hypothalamus and/or pituitary gland, to check for tumors or defects that may be the cause of CeH. They may perform genetic testing if the cause is unknown or you have a family history of the disease. 

Treatment

The standard treatment for central hypothyroidism is an oral medication called Synthroid, Levoxyl, Unithroid, or Levothroid (levothyroxine). This synthetic version of the thyroid hormone, thyroxine (T4), is taken daily to restore T4 to normal levels. Your healthcare provider will choose your initial dosage based on your body weight and the severity of your symptoms. 

Routine bloodwork is required frequently (every four to eight weeks) at the start of the medication to check thyroid hormone levels. Dosage adjustments will be made as needed based on test results and symptoms. Once your thyroid hormone levels are stabilized within normal ranges, monitoring will be required one to two times a year.

If a pituitary and/or hypothalamic disorder is the cause of central hypothyroidism, you may start treatment for the underlying cause before starting thyroid hormone replacement therapy. There is no cure for central hypothyroidism, so lifelong treatment may be required. 

Summary

Central hypothyroidism (Ceh) is a rare form of hypothyroidism caused by abnormal function of the pituitary gland, hypothalamus, or both, that cause the thyroid to produce insufficient hormone levels.

People with CeH may experience mild symptoms of hypothyroidism (e.g., fatigue) along with other symptoms such as recurrent headaches and vision disturbances (e.g., double vision). Symptoms of pituitary dysfunction may also be present.

A thorough physical examination and thyroid blood tests are required to diagnose central hypothyroidism accurately. Low T4 levels, with low, inappropriately normal TSH levels, are hallmark indicators of the condition. Thyroid hormone replacement therapy is the most common treatment for CeH. Levothyroxine, a synthetic version of thyroid hormone T4, is taken daily to restore and balance thyroid hormone levels and reduce symptoms. 

A Word From Verywell

Central hypothyroidism symptoms can interfere with your quality of life, but getting treatment can help manage the condition and improve your overall well-being. Talk to your healthcare provider if you have symptoms of hypothyroidism. They may refer you to an endocrinologist—a healthcare specializing in diagnosing and treating thyroid diseases—to provide an accurate diagnosis and recommend the best course of treatment.