Hypothyroidism

Definition

RMA SOP definition of Hypothyroidism

General information

Hypothyroidism is characterised by a reduction in circulating thyroid hormones and is reversible by thyroid hormone replacement therapy so that a normal thyroid state (euthyroid) is attained and hypothyroidism is no longer present.  Subclinical hypothyroidism is an asymptomatic condition which occurs when there are normal levels of thyroid hormone in the blood but a high level of thyroid stimulating hormone (TSH) is detected; this condition is a precursor to hypothyroidism.

Primary hypothyroidism, the most common form, results in a shrunken fibrotic thyroid gland.  Iatrogenic hypothyroidism, following radioactive iodine therapy or surgery for hyperthyroidism, is the second most common form of hypothyroidism.  Drugs used to treat hyperthyroidism (anti-thyroid drugs eg propylthiouracil and methimazole) can cause hypothyroidism, as can drugs containing iodine, such as amiodarone (an anti-arrhythmic drug).  Severe iodine deficiency in certain countries may lead to hypothryoidism.  Secondary and tertiary hypothyroidism are not common and occur when there is disease of the pituitary gland or hypothalamus respectively.

Hypothyroidism is also known as myxoedema.

Signs and symptoms

• fatigue, excessive sleepiness;
• depression;
• dull facial expression, drooping eyelids and slowness of speech;
• cold intolerance;
• weight gain;
• increased cholesterol levels;
• sparse, coarse, dry hair and coarse, scaly, dry, thick skin;
• forgetfulness and decreased concentration with a gradual change in personality;
• puffiness and periorbital swelling;
• cardiomyopathy.

Establishing onset

Onset is subtle and blood testing is required to confirm the diagnosis.  If a person was known to have hypothyroidism this would be recorded in doctors' notes and/or hospital records.  However, if these records have been destroyed or can no longer be obtained and there is a reliable history of hypothyroidism at a particular time, this generally will be accepted, unless there is contradictory evidence.  Obtain medical advice if it is unclear whether the claimed symptoms and treatment at that time can be attributed to hypothyroidism rather than to some other condition.

LAST REVIEWED FOR CCPS 18 JULY 2006.

PRELIMINARY QUESTIONS [31406]

22370 there is some evidence that hypothyroidism may be a factor in the development of the condition under consideration.

8806     the veteran has had hypothyroidism at some time.

9450     hypothyroidism means a disease state characterised by a reduction in circulating thyroid hormones. [Default true]

20856 the veteran had the identified illness or injury, a type of hypothyroidism, at the time of the clinical onset of the condition under consideration.

31407  the veteran has established the causal connection between hypothyroidism and VEA service for the clinical onset of the condition under consideration.

31408   the veteran has established the causal connection between hypothyroidism and operational service for the clinical onset of the condition under consideration.

or

31409   the veteran has established the causal connection between hypothyroidism and eligible service for the clinical onset of the condition under consideration.

CLINICAL ONSET AND OPERATIONAL SERVICE [31408]

8811     the identified illness or injury, a type of hypothyroidism, is causally related to operational service.

CLINICAL ONSET AND ELIGIBLE SERVICE [31409]

8812     the identified illness or injury, a type of hypothyroidism, is causally related to eligible service.