Name
THYROID-BINDING GLOBULIN DEFICIENCY
DESCRIPTION
DETAIL
THYROID BINDING PROTEIN DEFICIENCY STATES : 1. CONGENITAL : - TBG GENE DEFECTS - PARTIAL DEFICIENCY ( X LINKED ) & COMPLETE DEFICIENCY ( X LINKED ) - OTHER GENETIC DEFECTS - CARBOHYDRATE-DEFICIENT GLYCOPROTEIN SYNDROME TYPE 1 (CDG-1), WHICH IS AUTOSOMAL RECESSIVE 2. ACQUIRED CAUSES : - HYPERTHYROIDISM - NEPHROTIC SYNDROME - CHR RENAL FAILURE - CHR LIVER DISEASE - SEVERE SYSTEMIC ILLNESS ( EXCEPT HIV & AC INTERMITTENT PORPHYRIA ) - MALNUTRITION - ACROMEGALY( IN VERY RARE CASES ONLY ) - CUSHING SYNDROME - POORLY CONTROLLED DIABETES - DRUGS : ANDROGENS, STEROIDS, L-ASPARAGINASE -* SERUM TSH LEVELS - NORMAL * TOTAL T3 CONCENTRATIONS - LOW ( OCCASIONALLY ) * TOTAL T4 CONCENTRATIONS - LOW * FREE T4 LEVELS & FREE T3 LEVELS - NORMAL * THYROID BINDING GLOBULIN LEVELS - LOW IN PTS WITH TBG DEFICIENCY & INCOMPLETE ACQUIRED DEFICINECY, BUT THEY ARE UNDETECTABLE IN COMPLETE TBG DEFICIENCY ( MALES ONLY ). * UNDETECTABLE TBG LEVELS IN FEMALE PTS DENOTES LABORATORY ERROR OR THE VERY RARE OCCURENCE OF HOMOZYGOSITY FOR TBG GENE MUTATIONS IN GIRLS WITH TURNER SYNDROME ( XO KARYOTYPE). * IN PT WITH QUALITATIVE DEFECTS, THE TBG CONC MAY BE NORMAL. * SERUM TRIGLYCERIDE LEVELS - MILD TO MODERATELY ELEVATED IN 1/3 PTS
TYPENOTES
Medical Care The most important aspect of TBG deficiency is to recognize and correctly diagnose this condition in order to avoid unnecessary treatment for a mistaken diagnosis of hypothyroidism. A firm diagnosis of secondary TBG deficiency may be important when it indicates the coexistence of a previously unrecognized or underestimated serious general medical disease. Prompt evaluation of the possible causative conditions (see Thyroid bindingโprotein deficiency states) is mandatory. Surgical Care No surgical care is indicated or necessary. Consultations In cases of secondary TBG deficiency, referral to consultants should be made as appropriate for the evaluation and treatment of the primary disorder. A geneticist may be of value for selected cases of inherited TBG deficiency. Occasionally, referral to an endocrinologist is necessary because concomitant disease (eg, euthyroid sick syndrome, glucocorticoid therapy, concurrent thyroidopathy) may complicate the laboratory test picture in TBG deficiency, rendering the establishment of the diagnosis almost impossible without expert subspecialty input. Follow-up evaluations with the endocrinologist may be necessary until the concurrent illness subsides. Diet Dietary modification or any type of restriction is not necessary for this disorder. In cases of malnutrition/malabsorption, protein supplementation may be necessary. Activity No changes in the intensity or frequency of physical activity or exercise patterns are recommended or necessary.
RELATED DISEASE
Not Available Disease
DISEASE
INVESTIGATION
SERUM TRIGLYCERIDE, T3, T4, TSH, COMPLETE BLOOD COUNT, THYROXINE-BINDING GLOBULIN ( INFANTS), THYROXINE-BINDING GLOBULIN ( FEMALE ), THYROXINE-BINDING GLOBULIN ( MALE )