In
the following section we will discuss the comorbidity associated with hypothyroidism
Hypothyroidism
has been frequently associated with other diseases. These co-morbid states include
infertility, menstrual irregularities, Type 1 Diabetes Mellitus, depression, obesity,
hypercholesterolaemia, etc.
Hypercholesterolaemia
Impaired thyroid
function may be the cause of a hypercholesterolaemia. 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 hypertriglycereidaemia has been observed in
hypothyroid patients, particularly when they are obese.
Diabetes
Mellitus
Approximately 10% of patients with Type 1 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 goitre.
Infertility
Some patients
with infertility and menstrual irregularities have underlying subclinical or clinical
hypothyroidism. In some patients with elevated TSH levels, Thyroxine Replacement
Therapy may normalize the menstrual cycle and restore normal fertility.
Depression
The diagnosis of subclinical 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
subclinical. Also all patients on Lithium therapy need periodic thyroid evaluation
because Lithium may induce goitre and hypothyroidism.
Obesity
Some
obese patients may have hypothyroidism. Caloric needs due to hypothyroidism may
be responsible for weight gain in these persons.
In view of the strong association
between hypothyroidism and the above comorbid states, it is advisable to look
for hypothyroidism in these patients and screen accordingly through T4 and TSH
testing.
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