From the Guidelines
The daughter of a father with hypothyroidism has an increased risk of developing the condition, particularly if the father's hypothyroidism is caused by autoimmune thyroiditis (Hashimoto's), and management should include periodic screening with thyroid function tests (TSH and free T4) starting in adolescence or earlier if symptoms develop. The risk factors for an elevated TSH level include female sex, advancing age, white race, type 1 diabetes, Down syndrome, family history of thyroid disease, goiter, previous hyperthyroidism, and external-beam radiation in the head and neck area 1.
Key Points to Consider
- The most common cause of hypothyroidism in the United States is chronic autoimmune (Hashimoto) thyroiditis, which has a strong familial component, making vigilant monitoring important for at-risk family members.
- Symptoms to monitor include fatigue, weight gain, cold intolerance, constipation, dry skin, and menstrual irregularities.
- If hypothyroidism is diagnosed, treatment typically involves levothyroxine (synthetic T4) at a starting dose based on weight, taken on an empty stomach 30-60 minutes before breakfast.
- Regular monitoring of TSH levels is necessary, initially every 6-8 weeks until stable, then annually, with dose adjustments as needed to maintain TSH within the normal range (typically 0.4-4.0 mIU/L) 1.
Management and Screening
- The serum TSH test is the primary screening test for thyroid dysfunction, with multiple tests done over a 3- to 6-month interval to confirm or rule out abnormal findings.
- Follow-up testing of serum T4 levels in persons with persistently abnormal TSH levels can differentiate between subclinical and “overt” thyroid dysfunction.
- The optimal screening interval for thyroid dysfunction is unknown, but periodic screening starting in adolescence or earlier if symptoms develop is recommended for individuals with a family history of thyroid disease.
From the Research
Risk of Hypothyroidism in the Daughter of a Father with Hypothyroidism
- The risk of hypothyroidism in the daughter of a father with hypothyroidism is influenced by genetic and environmental factors 2.
- Hashimoto's thyroiditis, the most frequent autoimmune thyroid disorder, is the leading cause of hypothyroidism in iodine-sufficient areas, and about 20-30% of patients with Hashimoto's thyroiditis have a family history of the disease 2.
- A study on sibling recurrence risk in autoimmune thyroid disease found that the sibling risk ratio (lambda(s)) was 16.9 for autoimmune thyroid disease, indicating a significant genetic contribution to the development of the disease 3.
Management of Hypothyroidism
- The treatment of hypothyroidism consists of daily assumption of synthetic levothyroxine 2.
- Laboratory tests, including thyroid-stimulating hormone (TSH), free thyroxine, and thyroid peroxidase antibodies (TPO-Ab), are used to diagnose and manage hypothyroidism 4.
- Nutritional factors, such as iodine, iron, and selenium, play a crucial role in thyroid health, and appropriate status of these nutrients is essential to prevent and manage hypothyroidism 5.
Family History and Risk of Hypothyroidism
- A family history of thyroid disease constitutes a possible risk factor for congenital hypothyroidism in neonates with Down syndrome 6.
- Newborns with Down syndrome and a family history of thyroid disease have an eight-fold higher risk of congenital hypothyroidism 6.
- The risk of hypothyroidism in the daughter of a father with hypothyroidism may be higher due to the genetic contribution to the development of autoimmune thyroid disease 3.