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Jennifer A. Loh

Bio: Jennifer A. Loh is an academic researcher from MedStar Washington Hospital Center. The author has contributed to research in topics: Levothyroxine & Urine specific gravity. The author has an hindex of 3, co-authored 4 publications receiving 314 citations. Previous affiliations of Jennifer A. Loh include Georgetown University Medical Center.

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Journal ArticleDOI
TL;DR: If a specific serum TSH goal is desired, thereby avoiding iatrogenic subclinical thyroid disease, then fasting ingestion of levothyroxine ensures that TSH concentrations remain within the narrowest target range.
Abstract: Context: Patients treated with levothyroxine typically ingest it in a fasting state to prevent food impairing its absorption. The serum thyrotropin concentration is the therapeutic index of levothyroxine action. Objective: The study objective was to determine the effect of the timing of levothyroxine administration in relationship to food on serum thyrotropin levels. Design: Participants were randomized to one of six sequences, each consisting of three 8-wk regimens in a three-period crossover design. These regimens were in a fasting state, at bedtime, and with breakfast. The concentrations of TSH, free T4, and total T3 during each of the three timing regimens were documented. The primary outcome was the difference between serum TSH concentrations under fasting conditions compared with concentrations during the other 8-wk regimens. Setting: The study was conducted in an academic medical center. Participants: Study participants were receiving levothyroxine for treatment of hypothyroidism or thyroid cancer. Results: Sixty-five patients completed the study. The mean thyrotropin concentration was 1.06 ± 1.23 mIU/liter when levothyroxine was administered in the fasting state. When levothyroxine was taken with breakfast, the serum thyrotropin concentration was significantly higher (2.93 ± 3.29 mIU/liter). When levothyroxine was taken at bedtime, the serum TSH concentration was also significantly higher (2.19 ± 2.66 mIU/liter). Conclusion: Nonfasting regimens of levothyroxine administration are associated with higher and more variable serum TSH concentrations. If a specific serum TSH goal is desired, thereby avoiding iatrogenic subclinical thyroid disease, then fasting ingestion of levothyroxine ensures that TSH concentrations remain within the narrowest target range.

176 citations

Journal ArticleDOI
06 Mar 2009-Thyroid
TL;DR: The etiology of hypothyroidism plays a pivotal role in determining the timing and magnitude of thyroid hormone adjustments during pregnancy, and patients require vigilant monitoring of thyroid function upon confirmation of conception and anticipatory adjustments to LT(4) dosing based on the etiology.
Abstract: Background: In the United States, many women with hypothyroidism are on thyroid hormone replacement during pregnancy. The optimal management strategy for thyroid hormone dosing in hypothyroid women...

105 citations

Journal ArticleDOI
TL;DR: A 28-year-old woman presented with new-onset vertigo and diplopia that had started 2 weeks previously and underwent trans-sphenoidal resection of the brain mass without any significant intraoperative complications, and remains on desmopressin therapy for chronic diabetes insipidus.
Abstract: Postoperative diabetes insipidus usually occurs transiently, owing to temporary compromise of arginine vasopressin secretion. Sometimes, however, a triphasic pattern occurs: initial diabetes insipidus is followed by a period of inappropriate antidiuresis that finally culminates in chronic diabetes insipidus. The authors discuss the pathophysiology of this process and the importance of adjusting treatment according to the pattern of the disease. Background A 28-year-old woman presented with new-onset vertigo and diplopia that had started 2 weeks previously. An MRI scan of the brain revealed an 11 × 9 ×9 mm sellar mass that extended into the suprasellar region. Evaluation of pituitary function showed mild central hypothyroidism and secondary adrenal insufficiency. The patient underwent trans-sphenoidal resection of the mass without any significant intraoperative complications. On postoperative day 1 she abruptly developed polyuria, hypernatremia and urine hypo-osmolality. Investigations Measurements of plasma and urine osmolality, urine specific gravity, and serum sodium levels. Diagnosis Postoperative diabetes insipidus with a triphasic pattern. Management The patient's diabetes insipidus was initially treated with intravenous desmopressin, and her fluid status, serum sodium levels, and serum and urine osmolality were carefully monitored. During the second, antidiuretic phase, desmopressin was discontinued and the patient's fluid intake was restricted. After recurrence of diabetes insipidus during the third phase, the patient was treated with intranasal desmopressin and was discharged. She remains on desmopressin therapy for chronic diabetes insipidus.

72 citations


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Journal ArticleDOI
23 Sep 2011-Thyroid
TL;DR: The revised guidelines for the management of thyroid disease in pregnancy include recommendations regarding the interpretation of thyroid function tests in pregnancy, iodine nutrition, thyroid autoantibodies and pregnancy complications, thyroid considerations in infertile women, hypothyroidism in pregnancy and thyrotoxicosis in pregnancy.
Abstract: Background: Thyroid disease in pregnancy is a common clinical problem. Since the guidelines for the management of these disorders by the American Thyroid Association (ATA) were first published in 2...

2,409 citations

Journal ArticleDOI
TL;DR: Practice guidelines are presented for diagnosis and treatment of patients with thyroid-related medical issues just before and during pregnancy and in the postpartum interval, including evidence-based approaches to assessing the cause of the condition, treating it, and managing hypothyroidism.
Abstract: Objective: The aim was to update the guidelines for the management of thyroid dysfunction during pregnancy and postpartum published previously in 2007. A summary of changes between the 2007 and 2012 version is identified in the Supplemental Data (published on The Endocrine Society's Journals Online web site at http://jcem.endojournals.org). Evidence: This evidence-based guideline was developed according to the U.S. Preventive Service Task Force, grading items level A, B, C, D, or I, on the basis of the strength of evidence and magnitude of net benefit (benefits minus harms) as well as the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to describe both the strength of recommendations and the quality of evidence. Consensus Process: The guideline was developed through a series of e-mails, conference calls, and one face-to-face meeting. An initial draft was prepared by the Task Force, with the help of a medical writer, and reviewed and commented on by members of The Endocri...

1,707 citations

01 Jan 2011
TL;DR: Pregnancy is a stress test for the thyroid, resulting in hypothyroidism in women with limited thyroidal reserve or iodine deficiency, and postpartum thyroiditis inWomen with underlying Hashimoto’s disease who were euthyroid prior to conception.
Abstract: Pregnancy has a profound impact on the thyroid gland and thyroid function. The gland increases 10% in size during pregnancy in iodine-replete countries and by 20%– 40% in areas of iodine deficiency. Production of thyroxine (T4) and triiodothyronine (T3) increases by 50%, along with a 50% increase in the daily iodine requirement. These physiological changes may result in hypothyroidism in the later stages of pregnancy in iodine-deficient women who were euthyroid in the first trimester. The range of thyrotropin (TSH), under the impact of placental human chorionic gonadotropin (hCG), is decreased throughout pregnancy with the lower normal TSH level in the first trimester being poorly defined and an upper limit of 2.5 mIU/L. Ten percent to 20% of all pregnant women in the first trimester of pregnancy are thyroid peroxidase (TPO) or thyroglobulin (Tg) antibody positive and euthyroid. Sixteen percent of the women who are euthyroid and positive for TPO or Tg antibody in the first trimester will develop a TSH that exceeds 4.0 mIU/L by the third trimester, and 33%–50% of women who are positive for TPO or Tg antibody in the first trimester will develop postpartum thyroiditis. In essence, pregnancy is a stress test for the thyroid, resulting in hypothyroidism in women with limited thyroidal reserve or iodine deficiency, and postpartum thyroiditis in women with underlying Hashimoto’s disease who were euthyroid prior to conception. Knowledge regarding the interaction between the thyroid and pregnancy/the postpartum period is advancing at a rapid pace. Only recently has a TSH of 2.5 mIU/L been accepted as the upper limit of normal for TSH in the first trimester. This has important implications in regards to interpretation of the literature as well as a critical impact for the clinical diagnosis of hypothyroidism. Although it is well accepted that overt hypothyroidism and overt hyperthyroidism have a deleterious impact on pregnancy, studies are now focusing on the potential impact of subclinical hypothyroidism and subclinical hyperthyroidism on maternal and

1,464 citations

Journal ArticleDOI
TL;DR: Fifty-two evidence-based recommendations and subrecommendations were developed to aid in the care of patients with hypothyroidism and to share what the authors believe is current, rational, and optimal medical practice for the diagnosis and care of hyp Timothyroidism.

1,319 citations

Journal ArticleDOI
01 Dec 2014-Thyroid
TL;DR: It is concluded that levothyroxine should remain the standard of care for treating hypothyroidism and no consistently strong evidence for the superiority of alternative preparations is found.
Abstract: Background: A number of recent advances in our understanding of thyroid physiology may shed light on why some patients feel unwell while taking levothyroxine monotherapy. The purpose of this task force was to review the goals of levothyroxine therapy, the optimal prescription of conventional levothyroxine therapy, the sources of dissatisfaction with levothyroxine therapy, the evidence on treatment alternatives, and the relevant knowledge gaps. We wished to determine whether there are sufficient new data generated by well-designed studies to provide reason to pursue such therapies and change the current standard of care. This document is intended to inform clinical decision-making on thyroid hormone replacement therapy; it is not a replacement for individualized clinical judgment. Methods: Task force members identified 24 questions relevant to the treatment of hypothyroidism. The clinical literature relating to each question was then reviewed. Clinical reviews were supplemented, when relevant, with related...

1,128 citations