An Optimal Management Strategy for Hypothyroid Women During Pregnancy

1
An Optimal Management Strategy for Hypothyroid
Women During Pregnancy
Jennifer A. Loh, MD1,2 Leonard Wartofsky,
MD2 Jacqueline Jonklaas, MD1 Kenneth D.
Burman, MD2
1Department of Medicine, Georgetown University
Hospital, Washington, DC 2Georgetown University
Medical Center, Washington, DC
Georgetown University
Results (continued)
Abstract
Background There is controversy as how best to
manage thyroid hormone dosing in hypothyroid
women during pregnancy. Methods We conducted
a retrospective review of 45 pregnancies from 38
women with hypothyroidism from 1995-2007.
Results Patients treated for Graves disease
or goiter required the largest increases in LT4
(1st trimester 27, 2nd trimester 51, 3rd
trimester 45, p 0.005, 0.008, 0.007
respectively). Patients with primary
hypothyroidism required smaller dose increases of
11, 16 and 16 from baseline in each trimester
respectively (p values 0.014, 0.0008, 0.0008.
Average thyroid hormone dose increases for
patients with thyroid cancer were smaller than
expected, at 9, 21 and 26 in each trimester
(p0.012, 0.002, 0.001). Conclusions The
etiology of hypothyroidism plays a pivotal role
in determining the timing and magnitude of
thyroid hormone adjustments during pregnancy.
Patients should have vigilant, expectant
monitoring of thyroid function tests and empiric
dose increases should be avoided.
Table 1. Percentage of Patients Requiring
Levothyroxine Increases per Trimester of Pregnancy
Fig 4. TSH Values by Trimester for Patients with
Primary Hypothyroidism
Fig 3. Percent Increase in Thyroid Hormone for
Patients with Primary Hypothyroidism
Introduction
Adequate maternal thyroid function during
pregnancy is critical to the mother and
developing fetus. It has been suggested that
practitioners empirically increase thyroid
hormone levels by 30 as soon as conception
occurs to avoid sequelae of untreated maternal
hypothyroidism (1). However, this may over or
under-estimate maternal thyroid hormone needs.
Fig 6. TSH Levels by Trimester of Pregnancy in
Patients Treated for Graves' Disease or Goiter
Fig 5. Percent Increase in Levothyroxine Required
in Patients Treated for Graves' Disease or Goiter
Research Questions

• 1. Do patients with hypothyroidism truly require
  an increase in levothyroxine during pregnancy?
• 2. When does this increase occur and what is the
  magnitude of increase required?
• 3. Is there a difference in the timing or
  magnitude of increase based on the etiology of
  hypothyroidism?
• A retrospective review of 45 pregnancies from 38
  pregnant women with hypothyroidism, managed
  during pregnancy at the WHC and Georgetown
  Endocrine clinics 1995-2007 was performed.
  Patients were identified through physician recall
  and search of computerized medical records. IRB
  approval granted through Medstar Institute
• -Inclusion criteria
• - women with hypothyroidism followed for entire
  pregnancy
• - thyroid hormone doses recorded pre-pregnancy
  and during each trimester of pregnancy
• Exclusion criteria
• - thyroid hormone dose not recorded
• - thyroid function tests not recorded
  pre-pregnancy or during each trimester of
  pregnancy
• Thyroid hormone levels were titrated by the
  individual practitioners to maintain a goal
  thyrotropin within the normal range of 0.4-4.1
  ?iU/mL for all groups.

Methods
Fig 8. TSH Levels by Trimester of Pregnancy in
Patients with Thyroid Cancer
Fig 7. Percent Increase in Levothyroxine in
Patients with Thyroid Cancer
Results
Fig 1. Percent Increase in Thyroid Hormone Dosing
By Trimester of Pregnancy in All Patients
Conclusions

• Etiology of hypothyroidism most important
  determinant in calculating timing and magnitude
  of thyroid hormone adjustment during pregnancy
• An empiric dose increase of 30 may over or
  underestimate needs
• Patients with primary hypothyroidism required
  smaller and less frequent dose adjustments
  because of residual thyroid function
• Athyreotic patients require early, frequent
  thyroid function tests and aggressive titration
  of thyroid hormone due to lack of ability to self
  compensate for increased needs
• Patients with thyroid cancer required smaller
  dose increases due to higher average doses of
  thyroid hormone pre-pregnancy
• Pre-pregnancy counseling is recommended in young,
  hypothyroid women with vigilant monitoring of
  thyroid function tests and appropriate dose
  increases based on the etiology of hypothyroidism

plt0.01
Fig 2. TSH Levels by Trimester of Pregnancy for
Entire Group
References

• Alexander et al, N Engl J Med. 2004 Jul
  15351(3)241-9
• Abalovich, M. et al. JCEM 2007 92S1-47
• 3. Davis LE. Et al. Obstet Gynecol 1988
  72108-112