Case 72: Tiredness in pregnancy

 

Case 72: Tiredness in pregnancy

CASE 72: TIREDNESS IN PREGNANCY

History

A 27-year-old woman attends the antenatal clinic at 19 weeks’ gestation in her first ongoing

pregnancy, having had a termination at age 22 years. She is now happy to be pregnant.

She booked with the midwife at 8 weeks and has had normal booking bloods, blood pressure

and ultrasound scan.

She experienced nausea and vomiting until 14 weeks’ gestation. This has now settled but she

remains very tired and feels that she is gaining excessive weight in the pregnancy. She also

feels cold for much of the time, which surprises her as she understood that pregnant women

tend to feel hot.

Examination

The woman appears lethargic and of low mood. Her blood pressure is 115/68 mmHg and heart

rate 58/min. Abdominal examination is unremarkable, with the fundus palpable at the umbilicus.

INVESTIGATIONS

Normal range for

pregnancy

Haemoglobin 10.2 g/dL 11–14 g/dL

Mean cell volume 78 fL 74.4–95.6 fL

White cell count 7.9×109/L 6–16×109/L

Platelets 272×109/L 150–400×109/L

Thyroid-stimulating hormone (TSH) antibody 15 mu/L 0.5–7 mu/L

Free thyroxine (T4) 6 pmol/L 11–23 pmol/L

Questions

• What is the diagnosis and what features will you look for on examination?

• What are the implications for the mother and baby in pregnancy?

• How should the condition be managed?100 Cases in Obstetrics and Gynaecology

196

ANSWER 72

The full blood count shows mild anaemia, with relatively low mean cell volume. This is not

significant enough to account for the symptoms described.

The thyroid function tests confirm the clinical diagnosis of hypothyroidism. There is no history of radioactive iodine or surgical treatment, and Hashimoto’s thyroiditis is unlikely as

there has been no history of a hyperthyroid episode. This case therefore probably represents

idiopathic myxoedema.

The symptoms of tiredness, cold intolerance and weight gain may all relate to the hypothyroidism. In addition she may report dry skin, coarse hair, depression or constipation.

Examination may reveal relative bradycardia, blunted deep tendon reflexes or goitre.

Implications for the pregnancy and management

Hypothyroidism occurs in approximately 1 in 100 pregnancies, but this case is unusual in

that the diagnosis is made in pregnancy.

Myxoedematous coma is a very rare consequence of hypothyroidism, associated with a high

mortality rate. It is a medical emergency managed by supportive care and thyroxine supplementation. In the absence of a coma, thyroxine replacement is still needed and should be

titrated to the TSH and T

4 results.

In pregnancy, the thyroxine requirement may increase, and the TSH and T4 should be checked

every trimester once a maintenance regime has been established. The aim should be to keep

the TSH less than 5 mu/L.

(Although the thyroid-binding globulin increases in pregnancy, there is a compensatory rise

in tri-iodothyronine (T3) and T4 production such that the levels of free T3 and free T4 remain

similar to non-pregnant values.)

The fetus

Untreated hypothyroidism is associated with an increased risk of infertility, miscarriage,

stillbirth and pre-eclampsia. The fetal and neonatal outcome is generally good in women

diagnosed and treated appropriately. Anti-TSH antibodies may very rarely cross the placenta

and cause neonatal hypothyroidism, and this should be suspected if there are signs of neonatal goitre.

KEY POINTS

• Untreated hypothyroidism is associated with infertility, miscarriage, low birth

weight, fetal loss, pre-eclampsia and anaemia.

• Women established on thyroxine should have thyroid function monitored once in

each trimester of pregnancy.