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Congenital hypothyroidism is the most common cause of high levels of thyroid-stimulating hormone (TSH) in newborns. Learn about other causes
Congenital hypothyroidism is the most common cause of high levels of thyroid-stimulating hormone (TSH) in newborns.
If left untreated, congenital hypothyroidism can lead to prolonged neonatal jaundice, developmental delays, and mental retardation.
7 causes of high TSH levels in newborns
- Congenital hypothyroidism: Congenital hypothyroidism occurs when the thyroid gland fails to develop or function properly. In 80%-85% of cases, the thyroid gland is absent, severely reduced in size (hypoplastic), or abnormally located. Causes of congenital hypothyroidism may be the use of carbimazole, methimazole, and other antithyroid medications by the mother during pregnancy.
- Transient hypothyroidism: Transient hypothyroidism refers to a temporary deficiency of the thyroid hormone after birth (low T4 and elevated TSH levels), which corrects itself a few months after birth, during infancy.
- Congenital syndromes: Babies born with Pendred syndrome, Bamforth-Lazarus syndrome and brain-lung-thyroid syndrome have hypothyroidism as part of the disease.
- Premature birth: In one study, babies born prematurely had the highest TSH levels, and those with severe illness were at the highest risk of abnormally elevated TSH levels. Diseases that may result in higher TSH levels include:
- Respiratory distress syndrome
- Persistent ductus arteriosus (heart defect caused by problems in the development of the heart)
- Necrotizing enterocolitis (severe gastrointestinal problems)
- Maternal thyroid disorders or maternal medications: Thyroid disease in the mother can cause thyroid suppression in her children. Untreated Graves’ disease in the mother is one of the major causes of high TSH levels in newborns. Certain medications taken by the mother during pregnancy can also elevate TSH levels in babies.
- Iodine deficiency: Iodine deficiency in the diet is a major cause of congenital or transient hypothyroidism in newborns in many developing countries.
- Errors: Errors in the thyroid screening procedure or incorrect normal result intervals for that particular age are less common causes of high TSH levels in newborns.
What are signs of high TSH levels in newborns?
If hypothyroidism is not treated within 2 weeks, it can lead to following symptoms in babies:
- Uninterested in taking breast or bottle milk: They may fall asleep while feeding because it becomes hard for them to stay awake.
- Often quiet and seldom cry: They may sleep for hours and need to be awakened for feeding. They may not respond to stimulation or cry as much as other babies.
- Poor growth and poor weight gain: At birth, babies with high TSH levels are as large as a newborn infant, but gradually, they may start to lose weight.
- Slow heart rate and low blood pressure: Their hands and feet may be cold to the touch due to poor blood circulation.
- Jaundice: They may have yellowing of the skin that persists for quite some time. Their skin may also appear pale and blotchy.
Hypothyroidism can cause brain development delays, teething delays, milestone delays (due to weak muscles), and low intellectual ability. Timely intervention is therefore key.
How does treatment affect TSH levels in newborns?
If a baby has congenital hypothyroidism, doctors may prescribe a synthetic thyroid hormone (sodium levothyroxine or L-thyroxine). Within 4-5 days of treatment, positive changes that may seen in the newborn include:
- Increased urination, reducing puffiness and excess water weight
- Being more active, sleeping less, and crying more
- Improvement in appetite
- Improvement in skin color
- Achieving motor milestones that were delayed
Hypothyroidism in babies is a correctable and preventable cause of mental retardation. Early detection and management are very important.
