thyroid disease in pregnancy

Thyroid disease in pregnancy

Thyroid disease is the commonest pre existing endocrine disorder in pregnant female .it occur in 1% of the population.

MATERNAL PHYSIOLOGY

Increase TBG(thyroid binding globuline) due to increase oestrogen hormon synthesis.TBG bind 75% of thyroid hormone.
Increase total T3 and T4(result from the preipheral deiodination of T4and it is more potent than T4).
FREE T3(0.o5) and T4(0.04) unchanged.
TSH often suppressed.
Iodine deficiency in pregnancy secondary to increase loss through the kidney due to increase GFR and resullt in thyroid enlargment.
Thyroid function test in pregnancy
Measure FREE T3 and T4
TSH often suppressed and can be detected with new ultwasensitive assays.
HYPERTHYROIDISM
Incidence 1/500
It is usually due to GRAVES DISEASE,less than 5% result from toxic nodule ,thyroiditis or carcinoma.
GRAVES disease is associated with hyperplastic goiter often with exophthalmos.it is due to thyrotropin receptor stimulating antibodies.
The disease typically remit in the last 2 trimesters and 1/3 of cases treatment may be discontinued ,it may be exacerbated in the first trimester due to HCG levels.
Clinical features:
Typical signs of thyroidism are difficult to elicit in pregnancy but poor WT gain inspite of good appetite ,tachycardia more than 1oo BPM unresponsive to valsulva manoeuver may indicate the disease .other symptoms such as fatigue,heat intolerance are not useful.
COMPLICATION:A/maternal:thyroid storm,H.F,Hypertension.
B/fetal:increase preterm labour,IUGR,stillbirth.
Treaement:propylthyrouracil,carbimazole reduce the titer of thyroid Abs.
Both drugs are equally effective ,not teratogenic,can cause agranulocytosis so as sore throat should be thoroughly investigated.


TFT performed every 4-6 WKs
B-blockers are used to control symptoms.
Both drugs are safe in breast feeding.

HYOPTHYROIDISM

Occur in 1%
Usually due to hashimoto thyroiditis
Babies are normaly grown and do not seem to have increased risk of congenital anomalies.
hypoth. Can be associated with subfertility,recurrent miscarriage,low IQ.
TREATMENT:
thyroxin (safe in pregnancy and lactation).

Epilepsy

Incidence 1/1000(most common pre existing neurological condition)
Familial,cryptogenic,trauma related epilepsy account for the fast majority of cases.minority of cases are caused by brain tumor ,congenital abnormalities and vascular.
Seizure frequency may increase ,decrease or stay the same in pregnancy with labour being particularly high risk time for convulsion.
D.Dx of seizure in preg.and post partum
Idiopathic
Epilepsy secondary to specific causes e.g previous trauma
Intracranial infection :meningitis,encephalitis.
Vascular disease :CVA,pre-eclampsia.
Metabolic:liver and renal disease
drug toxicity:L.A e.g xylocain
Pseudo epilepsy
Managing epilepsy and preg.
PRE PREGNANCY:
The DX should be reviewed by neurologist especialy anti-epileptic drugs.
Cosideration should be given to stop AED(anti epileptic drugs) in those who are seizure free for more than 2 years.
Risk of relapse is 20-50%,serious health and social consequences may result from recurrence (e.g driving pro hibition).
When possible single AED should be tried to decreased teratogenicity and the lowest effective dose should be tried.
The risk to the mother and the fetus from non compliance is more than the risk ofAED.
FOLIC ACID (5 mg) taken each day 3 months before preg.


Antenatal management
Care should be carried out by an obsetrician specialist in epilepsy together with neurologist.
Screening for fetal anomalies should be offered especialy (NTD,cleft lip and palate ,CHD,microcephaly).
FOLIC acid 5 mg /day throughout preg.
Drug level monitored each trimester.
Oral vitamin k(10 mg/day) FROM 36 WKS to prevent haemorrhagic disease of new born .
If steroid are to be given for lung maturity a dose of 48 mg given instead of 24 mg in female taking enzume inducer AED(phenytoin,carbamazepine).
Intra partum care
Induction of labour and C/S indicated for the usual obstetrical indications.VD should be the aim
Labour carries a higher risk of seizure due to sleep disruption ,decrease intake and absorbtion of AED and hyperventilation.so adminster AED as usual.
If convulsion occur adminster anti convulsant.
Post partum care
Serum level of AED may rise in post partum peroid and monitoring may be necessory to prevent t oxic side effect .
Adequate sleep
Encourage breast feeding
1 mg vitamin k is given to the neonate to prevent HDN.
CONTRACEPTIVE advice :the enzyme inducer will reduce the efficacy of OCP,minipills,depoprovera.so high dose COP SHOULD be given with short pill-free interval (5-6) days instead of 7 days.
Depoprovera should be given every 10 wks instead of every 12 WKs.
Mirna is ideal contraceptive
female should ask for extra help for her neonate.
THE END
BY
TAHER ALI TAHER