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subacute lymphocytic thyroiditis
A poorly understood & uncommon cause of goitrous hyperthyroidism.
Etiology:
1) viral etiology suggested for sporadic form
2) autoimmune etiology suggested for postpartum form
Pathology:
1) foci of lymphocytic infiltration
2) increased interstitial fibrous tissue (occasional)
Clinical manifestations:
1) abrupt onset of hyperthyroidism
2) mild, goitrous enlargement of gland
3) painless thyroiditis
4) may progress to hypothyroidism
5) usually self-limited without sequelae
Laboratory:
1) increased T3 & T4
2) antithyroid microsomal Ab may be seen in low titers
3) erythrocyte sedimentation rate (ESR) normal or mildly elevated
4) antimicrosomal (thyroid peroxidase) antibody may be positive in postpartum form
Radiology:
- radioactive iodide uptake is low
Differential diagnosis:
- Graves disease
- subacute granulomatous thyroiditis
- multinodular goiter
- thyrotoxicosis after exposure to iodine containing contrast media [4]
- thyroid nodules
Management:
1) reassurance & observation
2) pharmacologic agents
a) propranolol 20-40 mg PO QID for hyperthyroidism
b) Synthroid 0.05 to 0.15 mg QD for hypothyroidism
c) prednisone 20-40 mg QD
1] severe cases not responding to other therapy
2] taper after 1 week with discontinuation in 2-4 weeks
3] restart if pain recurs
3) thyroidectomy for recurrent, disabling episodes
4) follow-up
a) 54% with persistent thyroid abnormality
b) anti-microsomal Ab positive postpartum thyroiditis generally resolves in 2-4 months
c) patients with postpartum thyroiditis should be monitored for development of hypothyroidism
d) anti microsomal antibody screening
1] prior history of postpartum thyroiditis
2] prior history of thyroid disease
Specific
postpartum thyroiditis
General
thyroiditis
hyperthyroidism
References
- Saunders Manual of Medical Practice, Rakel (ed),
WB Saunders, Philadelphia, 1996, pg 646-650
- Cotran et al Robbins Pathologic Basis of Disease,
5th ed. W.B. Saunders Co, Philadelphia, PA 1994 pg 1128
- Medical Knowledge Self Assessment Program (MKSAP) 11, 18,
American College of Physicians, Philadelphia 1998, 2018
- NEJM Knowledge+ Endocrinology