Free T4 test · Total T3 · Serum TSH -- Results are generally low in secondary hypothyroidism because the pituitary is damaged. However, normal or even high values may be seen. Additional laboratory abnormalities may include: Increased cholesterol ...

June 5, 2024 - In secondary hypothyroidism, free T4 and serum TSH are low (sometimes TSH is normal but with decreased bioactivity). Many patients with primary hypothyroidism have normal circulating levels of triiodothyronine (T3), probably caused by sustained ...

February 18, 2024 - Classic clinical features, including ... in most patients initially.[2] Characteristic laboratory findings of hypothyroidism include elevated TSH levels and low free T4 levels....

October 16, 2025 - Secondary hypothyroidism is treated by thyroid hormone replacement therapy. Synthroid, Levoxyl, Unithroid, and Levothroid (levothyroxine), synthetic versions of thyroxine (T4), are the most common hypothyroidism treatment. This oral medication is taken daily to restore and stabilize TSH and T4 levels to normal levels.

Secondary (or central) hypothyroidism is caused by disorders of the pituitary gland or hypothalamus. Generally, secondary hypothyroidism is associated with low TSH and low T3 and T4. However, TSH levels may also be normal or even slightly elevated.

August 13, 2025 - A diagnosis of central hypothyroidism may be made when there is an abnormally low TSH along with below-normal thyroxine (T4) and triiodothyronine (T3).2 A thyroid-releasing hormone (TRH)-stimulation test may help identify pituitary or hypothalamic ...

Learn about subclinical (borderline) thyroid conditions

August 14, 2022 - Opens in a new window Opens an external website Opens an external website in a new window · This website utilizes technologies such as cookies to enable essential site functionality, as well as for analytics, personalization, and targeted advertising. To learn more, view the following link: ...

June 8, 2020 - Occasionally, a low TSH may result from an abnormality in the pituitary gland, which prevents it from making enough TSH to stimulate the thyroid (secondary hypothyroidism). In most healthy individuals, a normal TSH value means that the thyroid ...

May 15, 2021 - Diagnosis is based on blood levels ... in primary causes (thyroid source); the TSH level may be normal to low in secondary (pituitary source) or tertiary (hypothalamic source) causes.5 Subclinical hypothyroidism describes the ...

BTF patient leaflet on thyroid function tests

September 8, 2025 - There is also a condition known as subclinical hypothyroidism which is the term used when patients have symptoms of hypothyroidism but only the TSH is abnormal. ... Genetic dysfunction: the thyroid may be dysfunctional at birth or is programmed to fail at some time in adult life – there is now evidence of a gene (DIO2) that causes issues with conversion of T4 to T3

Diagnostic evaluation of central hypothyroidism includes serum thyroid-stimulating hormone (TSH) and free thyroxine (T4) concentrations. In central hypothyroidism, free T4 is low and TSH may be low, normal, or minimally elevated.

Measurement of TSH and FT4 is required to identify secondary hypothyroidism.

Find out about an underactive thyroid (hypothyroidism), including the symptoms, treatments, possible complications and where to find support.

April 27, 2021 - Secondary hypothyroidism arises from pituitary or hypothalamic dysfunction, often due to pituitary adenomas, with low free T4 and variable TSH; specialist referral advised.

Negative feedback is absent, resulting in increased production of TSH. TSH is raised, and T3 and T4 are low. Secondary hypothyroidism, also called central hypothyroidism, is where the pituitary behaves abnormally and produces inadequate TSH, resulting in under-stimulation of the thyroid gland ...

May 31, 2021 - Secondary hypothyroidism, as stated above, is a condition in which the pituitary gland malfunctions, decreasing TSH production and, by extension, T3/T4 levels.

April 9, 2012 - AetiologyIodine deficiency remains the most common cause of hypothyroidism worldwide.4 However, in Australia and other iodine replete countries, autoimmune chronic&#x2026

March 23, 2023 - A small number of people with low thyroid have a problem with their pituitary gland. Their bodies do not produce enough TSH. When this happens, it’s referred to as secondary hypothyroidism.