FREQUENCY OF CONVERSION TO OVERT HYPOTHYROIDISM IN PATIENTS WITH AND WITHOUT SUBCLINICAL HYPOTHYROIDISM
Abstract
Background: Sub-clinical hypothyroidism (SCO) poses diagnostic and management difficulties forpathologists and clinicians. Cases of SCO are now diagnosed with increasing frequencies worldwide
mainly because of availability of more sensitive methods for serum TSH, total T3 and free T4 assays.
The rate of progression of SCO to overt hypothyroidism varies in different populations. Sub-clinical
hypothyroidism has been suggested as a risk factor for hypothyroid complications. There is a need to
identify and treat patients with SCO before they convert to overt hypothyroidism and develop
complications. Objective was to compare the development of overt hypothyroidism in a cohort of
patients of sub-clinical hypothyroidism and in subjects with normal thyroid function tests. Methods: It
was Cohort study conducted at Department of Chemical Pathology and Endocrinology, Armed Forces
Institute of Pathology, Rawalpindi. Hundred patients of SCO and almost equal number of age and sexmatched subjects with normal Thyroid function test (TFT) were enrolled as healthy controls. Subclinical hypothyroid patients and controls were followed for a period of one year on six monthly bases.
The patients were examined for signs and symptoms of hypothyroidism and serum TSH, total T3 and
free T4 were estimated. The clinical history, physical examination and thyroid function tests were
recorded on the pre-designed Performa. Results: Fourteen (14%) out of 100 cases of the SCO patients
developed overt hypothyroidism, SCO had 2.8 times more risk for conversion to overt hypothyroidism
as compared to healthy controls. Moreover female gender and initial levels of serum TSH were the
most important predictors for conversion of SCO to overt hypothyroidism. Conclusion: The frequency
of conversion to overt hypothyroidism in SCO patients approaches 14% and was more commonly
observed in female patients.
Keywords: Subclinical hypothyroidism, thyroid stimulating hormone, thyroid function tests, overt
hypothyroidism
References
Ringel MD, Mazzaferri EL. Subclinical thyroid dysfunction-can
there be a consensus about the consensus? J Clin Endocrinol
Metab 2005;90:588-90.
Woeber KA. Subclinical thyroid dysfunction. Arch Intern Med
;157:1065-8.
Hashmi S. Subclinical hyperthyroidism. Med Today 2004;2:132-5.
Halfand M. US Preventive Services Task Force. Screening of
subclinical thyroid dysfunction in non pregnant adults. A
summary of the evidence for the US Preventive Services Task
Force. Ann Intern Med 2004;140:128-41.
Col NF, Surks MI, Daniels GH. SCTD. Clinical applications.
JAMA 2004;291:239-43.
Smallridge RC. Disclosing SCTD: An approach to mild
laboratory abnormalities and vague or absent symptoms.
Postgrad Med 2000;107:143-52.
Surks MI, Chopra IJ, Mariash CN, Nicoloff JT, Solomon DH.
American Thyroid Association guidelines for use of laboratory
tests in thyroid disorders. JAMA 1990;263:1529-32.
Huber G, Staub JJ, Meier C, Mitrache C, Gugliemetti M, Huber
P et al. Prospective study of spontaneous course of SCO:
prognostic value of thyrotropin, thyroid reserve, and thyroid
antibodies. J Clin Endrocrinol Metab 2002;87:3221-6.
Cooper DS. Subclinical hypothyroidism. N Engl J Med
;345;260-5.
Hueston WJ, Pearson WS. Subclinical hypothyroidism and the
risk of hypercholesterolemia. Ann Family Med 2004;2:351-5.
Jukie T, Labar E, Kusie Z. Subclinical hypothyroidism. Acta Clin
Croat 2001;40:313-7.
Ijaz A, Marri MH, Qureshi AH, Qamar MA, Ali N. Pattern of
SCTD. J Coll Physicians Surg Pak 2002;12:86-8.
Caraccio N, Ferrannini E, Monzani F. Lipoprotein profile in subclinical hypothyroidism: response to levothyroxine replacement,
a randomized placebo-controlled study. J Clin Endocrinol Metab
;87:1533-8.
J Ayub Med Coll Abbottabad 2012;24(3-4)
http://www.ayubmed.edu.pk/JAMC/24-3/Anwer.pdf
Parle JV, Franklyn JA, Cross KW, Jones SC, Sheppard MC.
Prevalence and follow up of abnormal thyrotrophin (TSH)
concentrations in the elderly in the United Kindom. Clin
Endorinol 1991;34:77-83.
Diez JJ, Iglesias P. Spontaneous subclinical hypothyroidism in
patients older than 55 years: An analysis of natural course and
risk factors for development of overt thyroid failure. J Clin
Endrocrinol Metab 2004;89:4890-7.
Shrier DK, Burman KD. Subclinical hyperthyroidism:
controversies in management. Am Fam Physician 2002;65:431-8.
Gharib H, Tuttle RM, Baskin HJ, Fish LH, Singer PA,
McDermott MT. Subclinical thyroid dysfunction: a joint
statement on management from the American association of
clinical endocrinologists, the American Thyroid Association, and
the Endocrine Society. J Clin Endocrinol Metab 2005;90:581-5.
Vanderpump MP, Tunbridge WM, French JM. The incidence of
thyroid disorders in the community: a twenty-year follow-up of
the Whickham Survey. Clin Endocrinol 1995;43:55-68.
Sawin CT, Geller A, Kaplan MM, Bacharach P, Wilson PW,
Hershman JM. Low serum thyrotropin (thyroid-stimulating
hormone) in older persons without hyperthyroidism. Arch Intern
Med 1991;151:165-68.
Tenerz A, Forberg R, Jansson R. Is a more active attitude
warranted in patients with subclinical thyrotoxicosis? J Intern
Med 1990;228:229-33.
Woeber KA. Observations concerning the natural history of
subclinical hyperthyroidism. Thyroid 2005;15:687-91.
Canaris GJ, Manowitz NR, Mayor G, Ridgway EC. The
Colorado thyroid disease prevalence study. Arch Intern Med
;160:526-34.
Rosenthal MJ, Hunt WC, Garry PJ, Goodwin JS. Thyroid failure
in the elderly. Microsomal antibodies as discriminant for therapy.
JAMA 1987;258:209-13.
Glinoer D, Riahi M, Grun JP, Kinthaert J. Risk of subclinical
hypothyroidism in pregnant women with asymptomatic
autoimmune thyroid disorders. J Clin Endocrinol Metab
;79:197-204.
Moore DC. Natural course of '˜subclinical' hypothyroidism in
childhood and adolescence. Arch Pediatr Adolesc Med
;150:293-7.
Stott DJ, McLellan AR, Finlayson J, Chu P & Alexander WD.
Elderly patients with suppressed serum TSH but normal free
thyroid hormone levels usually have mild thyroid overactivity
and are at risk of developing overt hyperthyroidism. Q J Med
;78:77-84.
Diez JJ, Iglesias P, Burman KD. Spontaneous normalization of
thyrotropin concentrations in patients with subclinical
hypothyroidism. J Clin Endocrinol Metab 2005;90:4124-7.
Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH et
al. SCTD: scientific review and guidelines for diagnosis and
management. JAMA 2004;291:228-38.
Downloads
Published
How to Cite
Issue
Section
License
Journal of Ayub Medical College, Abbottabad is an OPEN ACCESS JOURNAL which means that all content is FREELY available without charge to all users whether registered with the journal or not. The work published by J Ayub Med Coll Abbottabad is licensed and distributed under the creative commons License CC BY ND Attribution-NoDerivs. Material printed in this journal is OPEN to access, and are FREE for use in academic and research work with proper citation. J Ayub Med Coll Abbottabad accepts only original material for publication with the understanding that except for abstracts, no part of the data has been published or will be submitted for publication elsewhere before appearing in J Ayub Med Coll Abbottabad. The Editorial Board of J Ayub Med Coll Abbottabad makes every effort to ensure the accuracy and authenticity of material printed in J Ayub Med Coll Abbottabad. However, conclusions and statements expressed are views of the authors and do not reflect the opinion/policy of J Ayub Med Coll Abbottabad or the Editorial Board.
USERS are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This is in accordance with the BOAI definition of open access.
AUTHORS retain the rights of free downloading/unlimited e-print of full text and sharing/disseminating the article without any restriction, by any means including twitter, scholarly collaboration networks such as ResearchGate, Academia.eu, and social media sites such as Twitter, LinkedIn, Google Scholar and any other professional or academic networking site.
