Transcript Trimester specific reference intervals of thyroid function tests among

TRIMESTER SPECIFIC REFERENCE
INTERVALS OF THYROID FUNCTION
TESTS AMONG NIGERIAN
PREGNANT WOMEN
Jibril M. El-Bashir, Randawa A.J,
Abbiyesuku F.M, Aliyu I.S, Akuyam
S.A, Manu M, Adamu R, Suleiman
H.M, Yusuf R, Mohammed A.
INTRODUCTION
• Thyroid disorders in pregnancy are harmful to maternal
and foetal health.
• Pregnancy has a profound impact on thyroid gland and
thyroid function.
• Normal pregnancy results in a number of hormonal
changes that affect thyroid function.
• hCG (a weak thyroid stimulator)surge in 1st trimester
and supresses TSH.
• Rise in oestrogen stimulates TBG synthesis with
increase in T3 and T4 .
• Measurement of free thyroid hormones not total is
necessary in pregnancy.
SIMILARITIES IN CLINICAL PRESENTATION
WITH NORMAL PREGNANCY
HYPERTHYROIDISM
• Anxiety
• palpitations
• dyspnoea
• sweating
• heat intolerance
• weakness
• irritability
• cardiac systolic murmurs
HYPOTHYROIDISM
• Lethargy
• weight gain
• constipation
NEED FOR PREGNANCY REFERENCE
INTERVALS
• American Thyroid Association (ATA)
recommends Establishment of Trimester
Specific Reference Intervals by each laboratory
for proper interpretation
• If that is not possible, clinicians should use
0.1 – 2.5, 0.2 – 3.0 and 0.3 – 3.0 µIU/ml for
TSH during 1st, 2nd and 3rd trimesters
respectively.
AIM
• To establish trimester-specific thyroid function
reference intervals in pregnancy among
Nigerian pregnant population.
METHODOLOGY
• Three-hundred apparently healthy pregnant
women were recruited into the study.
• Ages ranged between 14 – 40 years.
• Thyroid function tests (TSH, free T4, free T3 and
TBG) were assayed using ELISA kits.
• Trimester-specific reference intervals (2.5th and
97.5th centiles) were calculated for 1st , 2nd and
3rd trimesters’ respectively after log
transformation using Microsoft Excel software
2007.
RESULTS
Trimester Specific Reference Intervals for TSH and Free
T4 in subjects (2.5 and 97.5 percentiles)
• Subjects
n
TSH (µIU/L)
Free T4 (ng/mL)
• 1st trimester
75
(0.03 – 2.41)
(0. 84 – 2.06)
• 2nd trimester
125
(0.14 – 3.55)
(0.76 – 2.08)
• 3rd trimester
100
(0.21 – 3.12)
(0.70 – 1.70)
RESULTS
Trimester Specific Reference intervals for Free T3 and
TBG in subjects (2.5 and 97.5 percentiles)
• Subjects
n Free T3 (pg/mL)
TBG µg/mL
• 1st trimester
75 (1.92 – 3.51)
(11.32 – 43.17)
• 2nd trimester
125 (1.65 – 3.96)
(14.51 – 72.86)
• 3rd trimester
100 (1.74 - 3.65)
(20.33 – 72.55)
DISCUSSION
• Establishment of local reference values in
pregnancy is imperative for accurate diagnosis.
• In this study, TSH mirrored the change in free T4
• The values obtained here agree with ATA
suggested values and also with those obtained by
Panesar et al 2001, Haddow et al 2004, Stricker
et al 2007 and Bocos – Terraz et al 2009.
cont
• Samples from 120 reference individuals was
recommended by IFCC as minimum for
establishment of reference values.
• However, it was demonstrated by Horn et al
1998, Haddow et al 2004, Horrowitz et al
2008, and that less than 120 samples can be
used.
• This is an important limitation of the study.
CONCLUSION
• Thyroid disease in pregnancy is common,
clinically important and time sensitive.
• Hence, this study established Trimester
specific thyroid function reference intervals
for Nigerian pregnant population.
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