Impaired thyroid function may be the cause of a hypercholesterolemia. 

Clinical studies have shown that hypothyroid patients have significantly elevated serum cholesterol levels -from about 30% to 50% above control values.

Also increase in low density lipoprotein (LDL) cholesterol, modest fasting hypertriglycereidemia has been observed in hypothyroid patients, particularly when they are obese. 

Approximately 10% of patients with type I diabetes mellitus develop chronic thyroiditis in their lifetime which may include the insidious onset of subclinical hypothyroidism. 

Insulin requirements may change in the presence of subclinical hypothyroidism. 

It is important to examine patients with diabetes for the development of a goiter.

Some patients with infertility and menstrual irregularities have underlying subclinical or clinical hypothyroidism. 

In some patients with elevated TSH levels, thyroxin replacement therapy may normalize the menstrual cycle and restore normal fertility.

The diagnosis of sub clinical or clinical hypothyroidism must be considered in suspected patients with depression.

In fact, a small proportion of all patients who are depressed have primary hypothyroidism- either overt or sub clinical. 

Also all patients on lithium therapy need periodic thyroid evaluation because lithium may induce goiter and hypothyroidism.

Some obese patients may have hypothyroidism. 

Caloric needs due to hypothyroidism may be responsible for weight gain in these persons.