Thyroid disorders in pregancy

A)                  What tests for thyroid in Preg period  --if no evaluation of thyroid  was done preconceptionaly? Ans: Ideally in such a situation the concerned obstetrician should insist on assays of a) free t4, b) free t3 & c) TPO ab. Immunoradiometric assay of TSH will be more informative & helpful in initiating dosage & onward treatment. Because traditional method may fail to detect all cases of hypothyroidism though most Lab have already switched over to hypersensitive TSH assay. Less than 1% of circulating t4 & t4 ARE IN FREE FORM (akin to free Testosterone). AND REST thyroid hormones are BOUND TO TBG WHICH IS INCREASED IN PREG.

B)                  What damage the foetus can incur in this woman who reported for the first time in preg a TSH level of 150 without previous thyroid evaluation In such a case the following events can happen, but remind you-my dear members - not in all cases:-a) increase risk of miscarriage in this case –may be at late first trimester (already 12 wks) or later b) What is more relevant that there can be a toddler with low IQ-which is difficult to diagnose during conception. . As such, one can’t counsel for MTP on presumptive basis in the case cited.

C)                  Fallacies in interpreting TSH (due to rise of β-hCG), T4 & T4 values in first trimester:-In addition to transient decrees of TSH in almost all euthyroid women in early preg (8-14 weeks).Hyperemesis causes apparently low TSH & falsely raised Free T4 (there is rise hepatic synthesis of TBG-about 2-3 fold rise of serum TBG --compensatory rise of T4& T3):--That is why people insists on free values. Before I conclude , let me say that  in this particular case TSH may be as high as 200-225 mcg in this particular woman had/ is still having  hyperemesis even at 12 weeks—well then TSH may be  as much as 60%  less than its original .Imagine the degree of hypothyroidism (Florid case)! Rarely TSH may rise in early pregnancy. This has been observed in about 20% cases.

D)                  

E)                   What foetal damage in cases with SCH?  Even lower IQ has been observed in women where SCH was left untreated, in comparison to those with normal anti-TPO ab.!!!

F)                   When foetus does initiates thyroxine production? Before 12 weeks of gestation foetus is dependent on maternal thyroid hormones including brain dev...

 

Fallacies in interpreting TSH (due to rise of β-hCG), T4 & T4 values in first trimester:-In addition to transient decrees of TSH in almost all euthyroid women in early preg (8-14 weeks).Hyperemesis causes apparently low TSH & falsely raised Free T4 (there is rise hepatic synthesis of TBG-about 2-3 fold rise of serum TBG --compensatory rise of T4& T3):--That is why people insists on free values. Before I conclude , let me say that  in this particular case TSH may be as high as 200-225 mcg in this particular woman had/ is still having  hyperemesis even at 12 weeks—well then TSH may be  as much as 60%  less than its original .Imagine the degree of hypothyroidism (Florid case)! Rarely TSH may rise in early pregnancy. This has been observed in about 20% cases.

 

Iodine metab in Preg: - India is an iodine def country (Sub-Himalayan belt in particular) & Arsenic excess country. Iodine excretion increases in preg. Iodine fortification in common salt is an India Govt. National programme & so also universal screening of neonates along with some other metab screen.

Exclude Pernicious anaemia: - Such type of anemia may coexist incases with autoimmune Thyroid diseases. (Presence of microsomal ab).  May have to exclude that especially if anaemia becomes iron resistant.

Dose adjustment in preg-How? We should pay more reliance on TSH level in late second trimester or third tribe cause at that phases of pregnancy –because there can be physiological rise of TSH in late preg. So one should be cautious.   

If we ignore a TSH report of 150 mcg as in this case And or woman concerned declines to ingest LT4 then what maternal damage may ensue? PH, Abruption, PTL & Postpartum thyroid dysfunction-which is often misdiagnosed.

The practical problem is that in the busy chambers of endocrinologists (due possibly to epidemic of DM in our country –) it is becoming increasingly difficult to have an appointment of endocrinologist. How long a preg mother can wait at a chamber / if reefed. From one OPD to other Deptt.  Therefore WE have to treat hypothyroid cases of our own. That is the reason why I am posting all these rubbish (!) for quick brushing up knowledge on thyroid metab of our dear Forum members.