THYROID Volume 2, Number 1, 1992 Mary Ann Liebert, Inc., Publishers
Postpartum Thyroid Dysfunction:
Comment
JOHN H. LAZARUS
report by Learoyd et al. is a comprehensive review of a subject that many thyroidologists have tended to dismiss because of its alleged transient nature and alleged clinical insignificance. The authors state that thyroid dysfunction is strongly associated with antimicrosomal or antithyroglobulin antibodies. I would to further and suggest that it is invariably, associated with the presence of thyroid antibodies, usually antiperoxidase but occasionally anti-thyroglobulin, as found in a recent study (1). The purported finding of cases with negative antibodies may confound prevalence figures and may have accounted for the high figure in the Welsh study (2). There is a need to standardize the antibody assays. Indeed 12 of 49 of their cases were thyroid antibody negative. In that study, postpartum thyroid dysfunction was defined on the basis of two or more consecutive abnormal tests. However, this definition is open to debate. For example, is a patient thyrotoxic when the T3 is just outside 2 SD above the control mean but the TSH is not suppressed? In my view, it is more meaningful to show the reciprocal change of TSH with a high T3 (for hyperthyroidism) and a low T4 for hypothyroidism. Definition is important. In addition to the study of Pop et al. (3) relating depression to postpartum thyroid dysfunction, we have shown recently that in a carefully controlled study, depressive symptomatology was associated with antiperoxidase antibodies whether thyroid dysfunction occurred or not (4). The biologic significance and mechanism of this link is not clear at this time.
I agree with the suggestion that PPTD is predictive of subsequent thyroid failure, but the relative importance of other factors that lead to failure in these patients is unclear. PPTD is a useful model of autoimmune thyroid disease where one can observe the patient before the disease occurs. Future research should take advantage of this chronology.
This
University of Wales College of Medicine,
REFERENCES 1. Adams H, et al 1991 Quantitative and qualitative thyroid sonography in postpartum thyroiditis. Proceedings of 10th International Thyroid Congress, The Hague, p 58. Abstr99. 2. Fung HYM, et al 1988 Postpartum thyroid dysfunction in midGlamorgan. Br Med J 296:241. 3. PopVJM.etai 1991 Postpartum thyroid dysfunction and depression in an unselected population. N Engl J Med 324:1815. 4. Othman S, et al 1991 Postpartum thyroiditis is associated with psychiatric illness. Proceedings of IOth International Thyroid Congress, The Hague, p 58, Abstr 98.
Address reprint requests to: Dr. John H. Lazarus Department of Medicine University of Wales College of Medicine Heath Park Cardiff CF4 4XN, Wales, United Kingdom
Heath Park, Wales, UK
81
Postpartum Thyroid Dysfunction:
Comment
JOHN H. LAZARUS
report by Learoyd et al. is a comprehensive review of a subject that many thyroidologists have tended to dismiss because of its alleged transient nature and alleged clinical insignificance. The authors state that thyroid dysfunction is strongly associated with antimicrosomal or antithyroglobulin antibodies. I would to further and suggest that it is invariably, associated with the presence of thyroid antibodies, usually antiperoxidase but occasionally anti-thyroglobulin, as found in a recent study (1). The purported finding of cases with negative antibodies may confound prevalence figures and may have accounted for the high figure in the Welsh study (2). There is a need to standardize the antibody assays. Indeed 12 of 49 of their cases were thyroid antibody negative. In that study, postpartum thyroid dysfunction was defined on the basis of two or more consecutive abnormal tests. However, this definition is open to debate. For example, is a patient thyrotoxic when the T3 is just outside 2 SD above the control mean but the TSH is not suppressed? In my view, it is more meaningful to show the reciprocal change of TSH with a high T3 (for hyperthyroidism) and a low T4 for hypothyroidism. Definition is important. In addition to the study of Pop et al. (3) relating depression to postpartum thyroid dysfunction, we have shown recently that in a carefully controlled study, depressive symptomatology was associated with antiperoxidase antibodies whether thyroid dysfunction occurred or not (4). The biologic significance and mechanism of this link is not clear at this time.
I agree with the suggestion that PPTD is predictive of subsequent thyroid failure, but the relative importance of other factors that lead to failure in these patients is unclear. PPTD is a useful model of autoimmune thyroid disease where one can observe the patient before the disease occurs. Future research should take advantage of this chronology.
This
University of Wales College of Medicine,
REFERENCES 1. Adams H, et al 1991 Quantitative and qualitative thyroid sonography in postpartum thyroiditis. Proceedings of 10th International Thyroid Congress, The Hague, p 58. Abstr99. 2. Fung HYM, et al 1988 Postpartum thyroid dysfunction in midGlamorgan. Br Med J 296:241. 3. PopVJM.etai 1991 Postpartum thyroid dysfunction and depression in an unselected population. N Engl J Med 324:1815. 4. Othman S, et al 1991 Postpartum thyroiditis is associated with psychiatric illness. Proceedings of IOth International Thyroid Congress, The Hague, p 58, Abstr 98.
Address reprint requests to: Dr. John H. Lazarus Department of Medicine University of Wales College of Medicine Heath Park Cardiff CF4 4XN, Wales, United Kingdom
Heath Park, Wales, UK
81
