Thyroid function tests abnormalities

Thyroid function tests abnormal thyroid hormone levels may suggest hypo- or hyperthyroidism, either of which may be associated with constipation. 

Patients with metastatic renal cell carcinoma commonly develop mild biochemical thyroid function test abnormalities while taking sorafenib. However, compared with sunitinib, which is associated with a high incidence of thyroid dysfunction, making routine monitoring necessary, patients taking sorafenib need thyroid function monitoring only if clinically indicated (1074). 

What would you tell GD regarding the cause of her signs and symptoms, significance of her abnormal thyroid function tests, and therapeutic options ... 

Thyroid function tests are often altered by somatropin because of increased conversion of T4 to T3, but this is clinically insignificant at low doses (SEDA-21, 453). One child with Prader-Willi syndrome had a fall in serum thyroxine concentration during somatropin therapy and needed thyroxine replacement (33). Hypothyroidism developed in 11 of 46 growth hormone-deficient children treated with somatropin (34). Prior abnormalities in hypothalamic-pituitary function and alterations in thyroid hormone metabolism, probably both, contributed to the high incidence of hypothyroidism, which was similar to that in previous studies. 

Amiodarone causes altered thyroid function tests, with rises in serum concentrations of T4 and reverse T3 and a fall in serum T3 concentration. This is due to inhibition of the peripheral conversion of T4 to T3, causing preferential conversion to reverse T3. These changes can occur in the absence of symptomatic abnormalities of thyroid function. 

A 72-year-old woman with dilated cardiomyopathy was given amiodarone for fast atrial flutter and 6 months later developed abnormal thyroid function tests, with a suppressed TSH and a raised serum thyroxine. The autoantibody profile was negative and a thyroid uptake scan showed reduced uptake (44). 

Since the measurement of serum T3 and T4 concentrations may not be helpful, an alternative would be to measure metabolic status. Measurement of the serum concentration of co-enzyme Q10 may distinguish patients with clinical thyroid dysfunction from those who simply have abnormalities of thyroid function tests (49), but the value of this test remains to be established. 

A 30-year-old woman took mefloquine, 250 mg/week, and developed abdominal pain, palpitation, and tremor thyroid function tests were abnormal 1 month after withdrawal the tests had returned to normal (SEDA-18, 289). 

Tamaskar IR, Unnithan J, Garcia JA, Dreicer R, Wood L, Iochimescu A, Bukowski R, Rini B. Thyroid function test (TFT) abnormalities in patients (pts) with metastatic renal cell carcinoma (RCC) treated with sorafenib. ASCO Annual Meeting Proceedings. J Clin Oncol 2007 25 (June 20 Suppl) 5048. 

Abnormal thyroid function test results Absence of flaccid paralysis dysphonia without bulbar palsies Absence of bulbar palsies and acute flaccid paralysis... 

The low Tj syndrome observed after major trauma may also be related to changes in selenium status affecting the activity of iodothyronine deiodinase, with selenium supplements reversing most of the biochemical abnormalities found in thyroid function tests. ... 

As patients recover from NTIs, many of the thyroid test abnormalities revert to normal. Total T4 concentrations will be corrected first followed by a rise in T3. Serum TSH may also transiently rebound to high concentrations for several days or weeks before returning to normal. Thus, in NTI, abnormal thyroid function test results do not necessarily indicate the presence of thyroid disease, but may demonstrate adaptations to the catabolic state. Conversely, paradoxically normal values may be seen in patients with thyroid disease as a result of medications or nonthyroidal illness per se. Assessments of thyroid function in ill patients are best postponed until the illness resolves, unless a diagnosis would affect patient outcome. 

TBG is the thyroid hormone-binding protein having the greatest affinity for T4. As such, it is very important in regulating the concentration of the FT4 hormone. Estrogen-induced TBG excess and congenital TBG deficiency are the most significant TBG abnormalities that affect the interpretation of thyroid function test results (see Box 52-1). 

Jabbar MA, Larrea J, Shaw RA. Abnormal thyroid function tests in infants with congenital hypothyroidism The influence of soy-based formula. J Am Coll Nutr 1997 16 280-282. 

Abnormalities in thyroid function tests may be encountered in a variety of severe nonthyroidal illnesses, either acute or chronic, and some of the abnormalities are mediated through decreases in TBPA or in TBG, or in both binding proteins. Where the abnormality is due only to decrease in TBG and TBPA, the FTI, FTC, and similar measurements are normal but total T4 in serum is low and the resin uptake of T3 is elevated. This is the situation in chronic renal disease and although the FTI and similarly calculated free T4 factors do not give normal results in all patients, the free T4 concentration is normal in nearly all euthyroid patients (J3). 

Baseline tests CBC, hepatic function, pregnancy test, TSH, renal function, uric acid, HCVRNA level. Exclusions to treatment platelet count <90,000 cells/mm (as low as 75,000 cells/mm in patients with cirrhosis) absolute neutrophil count < 1,500 cells/mm serum creatinine concentration > 1.5 X upperlimit of normal abnormal thyroid function... 

Dysregulation of the hypothalamic-pituitary-thyroid axis causes a reduction in thyroid function. There may be a relationship between an abnormal TSH response to TRH and depressive symptoms. Thus, unipolar patients undergoing the TRH-TSH test (which measures the difference between baseline TSH and peak postinfusion TSH after they are given synthetic TRH) reportedly have a blunted response, whereas bipolar, depressed patients have an elevated response (see also Chapter 1,... 

Peripheral edema insomnia, headache fever, chills lipid abnormalities, increased triglycerides, cholesterol, reduced high-density lipoproteins hypothyroidism (reduced thyroxine, thyroid-stimulating hormone) diarrhea low emetogenic potential leukopenia and anemia dry skin increased liver function tests pancreatitis... 

---