Thyroid Function tests

Central hypothyroidism

The use of thyroid function tests in the diagnosis of hypopituitarism: definition and evaluation of the TSH Index. (clin endo | pubmed | medscape:free full text)
body-weight-adjusted treatment 17711927;

AACE (Am Assoc of Clin Endocrinologists) 2006: Med Guidelines for Clin Practice for the Diagn and Managem of thyr nodules: pdf
BTS/RCP 2007: Guidelines for the management of thyroid cancer (2 ed): pdf

http://www.endo-society.org/guidelines/final/upload/Clinical-Guideline-Management-of-Thyroid-Dysfunction-during-Pregnancy-Postpartum.pdf [+attached]
Recommendations

both overt and subclin hypothy: adverse effects on course of pregnancy and developmt of fetus
hypothy should be corrected before initiation of pregnancy (aim TSH<2.5U/L)
replacemt dose should be augmented early during pregnancy (by 4-6/40 by 30-50%)
euthyroidism should be maintained throughout pregnancy (aim TSH<2.5U/L 1st trim, <3U/L 2nd/3rd trim)
overt maternal hypothy: a/w damage to fetal intellectual developmt (whether subclin hypothy does, uncertain, but should be treated): need to be corrected ASAP, rpt TFT within 30-40d
subclin hypothy: tx improves obstetric outcome (but not yet proven to improve fetal neurological developmt): LT4 tx recommended

PTU as first line Tx for hyperthy dur pregnancy (methimazole a/w fetal developmtl abnmlties esp 1st trimester, but may be used if pt intolerant to PTU)
Dx or PMHx of maternal Graves' carries risk for fetus
ATD tx to mother can induce fetal hypothy
transplacental passage of TRAb can cause fetal hyperthy
ATD tx: target maternal fT4 at non-pregnant ULN usu'ly protects fetus from hypothy
close monitoring of T4, TSH, TRAb, and fetal US incl thyroid recommended for guiding therapy
fetal hyperthy does not occur when TRAb levels are nml and ATD tx is not administered
surgery may be required in some instances (with preop preparation with PTU, propranolol and iodine; ideally during 2nd trim)

a/w icrd thyroid hormone levels and TSH suppression, pts occasionally thyrotoxic
thy hormone level elevation and gestational hyperthyroidism: usu self-remitting, mostly not requiring Tx
subclin hyperthy (in this setting) does not require tx, and tx is advised against b/o risk of inducing fetal hypothy

Bx under US guidance, if appropriate surgery during mid-trimester (delay in tx of low-grade tu until after delivery not considered a danger), pregnancy not thought to adversely affect course of thy malignancy
TSH suppression for known thy malignancy: maintain during pregnancy with detectable TSH and T4 at upper end of range for nml pregnancy
RAI: not during pregnancy or during lactation

only 1 study showed dcr in miscarriage and preterm delivery with LT4 tx of euthyroid AB pos women;
at risk of developing hypothy dur pregnancy

TRAb: to be checked before preg/ by end of 2nd trim in mother with current or previous Graves' txd with thryoidectomy or RAI, or previous neonate with ,

Infectious: {acute|chronic}{suppurative|non~}=septic
DeQuervain's=Subacute=granulomatous: enlarged, tender thyroid, RAIU near zero, icrd T4 and Tg, hi ESR; likely viral, lasts for weeks/months, often recurs
Autoimmune:

Hashimoto's=chronic=lymphocytic: usu persists for years
also: painless=silent=postpartum: overlapping features of DeQuervain's and Hashimoto's

Riedel's thyroiditis=chron sclerosing=invasive fibrous: overgrowth of connective tissue, often extending into neighbouring structures: extremely hard thyroid
Misc: Sarcoid; Amyloid; Radiation; Trauma