A017

Hypothyroidism causing Hypercholesterolemia

Sheenam, O Mitrofanova, VG Aarella, United Lincolnshire Hospitals NHS Trust

Introduction: Hypothyroidism is one of the main causes of high cholesterol and it should not be missed on initial assessment of hypercholesterolemia. The treatment for high cholesterol may be delayed to wait until the thyroid treatment is optimal, as this often brings the cholesterol levels down on its own and so removes the need for statins.

Abstract: We describe the case of a 60 year old female who was referred to the Endocrinology clinic with complaints of increasing tiredness, lethargy and weight gain (about three stones over one year) and hypercholesterolemia on blood tests. She was on Atorvastatin 20 mg for 8 months but had persistent hypercholesterolemia.

Investigations:Total cholesterol- 7.8 mmol/L, Triglyceride- 2.5 mmol/L, HDL-1.7 mmol/L, LDL-5.0 mmol/L and Total: HDL cholesterol ratio of 4.6. HbA1c was slightly high at 45 mmol/mol, primary hypothyroidism with TSH 18.3 mU/L and free T4 5.7 pmol/L.

Management: Levothyroxine was added to the treatment and follow up blood tests were requested. Following commencement of treatment with Levothyroxine, her cholesterol levels came within normal range as reflected on repeat blood tests.

Investigations:

 

Test Name

Results prior to Levothyroxine

Results after Levothyroxine

Total Cholesterol (mmol/L)

7.8

3.8

Triglyceride (mmol/L)

2.5

1.7

HDL (mmol/L)

1.7

1.1

LDL (mmol/L)

5.0

1.9

Total: HDL cholesterol ratio

4.6

3.5

TSH (mU/L)

18.3

2.1

Free T4 (pmol/L)

5.7

15.8

She has been having repeat blood tests for thyroid profile and cholesterol and with Levothyroxine 100mcg and Atorvastatin 20mg, her Cholesterol and Thyroid function tests both are in normal range.

 

Key learning:

Hypercholesterolemia in a patient can point towards underlying hypothyroidism as thyroid hormones, especially T3, play an essential role in helping the liver process and remove any excess cholesterol from the body. When the body does not produce enough thyroid hormones, the liver cannot process as much cholesterol as it should, hence resulting in hypercholesterolemia.

An underactive thyroid leads to a decrease in metabolism and cessation in the breakdown and removal of LDL. As a result, the bloodstream will have an increase in LDL and total cholesterol which can start to build up. Even mildly low thyroid hormone levels (subclinical hypothyroidism) can lead to high cholesterol.

The resulting hypercholesterolemia can then lead to more complications, like- atherosclerosis, heart diseases or stroke, if not managed timely.

Because of the clear thyroid and cholesterol connection, it is very important to prevent complications like cardiovascular disease especially when suffering from hypothyroidism.