Biomaterial Database

The effect of serum dilution on free thyroxine (T4) concentration in the low T4 syndrome of nonthyroidal illness. 1985

J C Nelson, and R M Weiss

Progressive dilution of normal sera causes little change in free T4 concentrations. Similar dilution of sera containing drug inhibitors of T4 binding to serum proteins causes a progressive fall in free T4. The low T4 syndrome of nonthyroidal illness is thought to be associated with a circulating inhibitor(s) of T4 binding. It would be expected, therefore, that dilution of sera from the low T4 syndrome might also result in a fall in free T4 concentrations. We compared the effect of progressive serum dilution on free T4 concentrations in low T4 syndrome sera to those in normal, hyperthyroid, pregnancy, TBG-deficient and salicylate-containing sera. A tracer dialysis method proved inappropriate for studying dilution effects. Using a new dialysate RIA method to measure free T4, we found a progressive fall in free T4 concentrations in sera from patients with the low T4 syndrome similar to that in serum containing salicylate, but not to that in normal sera. The magnitude of the fall varied widely among individual patients. Free T4 methods which use a diluted serum sample will underestimate free T4 concentrations in the low T4 syndrome.

UI	MeSH Term	Description	Entries
D006980	Hyperthyroidism	Hypersecretion of THYROID HORMONES from the THYROID GLAND. Elevated levels of thyroid hormones increase BASAL METABOLIC RATE.	Hyperthyroid,Primary Hyperthyroidism,Hyperthyroidism, Primary,Hyperthyroids
D007037	Hypothyroidism	A syndrome that results from abnormally low secretion of THYROID HORMONES from the THYROID GLAND, leading to a decrease in BASAL METABOLIC RATE. In its most severe form, there is accumulation of MUCOPOLYSACCHARIDES in the SKIN and EDEMA, known as MYXEDEMA. It may be primary or secondary due to other pituitary disease, or hypothalamic dysfunction.	Central Hypothyroidism,Primary Hypothyroidism,Secondary Hypothyroidism,TSH Deficiency,Thyroid-Stimulating Hormone Deficiency,Central Hypothyroidisms,Deficiency, TSH,Deficiency, Thyroid-Stimulating Hormone,Hormone Deficiency, Thyroid-Stimulating,Hypothyroidism, Central,Hypothyroidism, Primary,Hypothyroidism, Secondary,Hypothyroidisms,Primary Hypothyroidisms,Secondary Hypothyroidisms,TSH Deficiencies,Thyroid Stimulating Hormone Deficiency,Thyroid-Stimulating Hormone Deficiencies
D007201	Indicator Dilution Techniques	Methods for assessing flow through a system by injection of a known quantity of an indicator, such as a dye, radionuclide, or chilled liquid, into the system and monitoring its concentration over time at a specific point in the system. (From Dorland, 28th ed)	Dilution Techniques,Dilution Technics,Indicator Dilution Technics,Dilution Technic,Dilution Technic, Indicator,Dilution Technics, Indicator,Dilution Technique,Dilution Technique, Indicator,Dilution Techniques, Indicator,Indicator Dilution Technic,Indicator Dilution Technique,Technic, Dilution,Technic, Indicator Dilution,Technics, Dilution,Technics, Indicator Dilution,Technique, Dilution,Technique, Indicator Dilution,Techniques, Dilution,Techniques, Indicator Dilution
D008297	Male		Males
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011863	Radioimmunoassay	Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.	Radioimmunoassays
D003956	Dialysis	A process of selective diffusion through a membrane. It is usually used to separate low-molecular-weight solutes which diffuse through the membrane from the colloidal and high-molecular-weight solutes which do not. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Dialyses
D004573	Electrolytes	Substances that dissociate into two or more ions, to some extent, in water. Solutions of electrolytes thus conduct an electric current and can be decomposed by it (ELECTROLYSIS). (Grant & Hackh's Chemical Dictionary, 5th ed)	Electrolyte
D005260	Female		Females