Use of radionuclides in clinical endocrinology.

Radionuclides provide sensitive reporter molecules for labeling pharmaceuticals. Hormone measurements using radioimmunoassays are commonplace today, increasing our understanding of the pathophysiology of endocrine disease. In turn, hormones tagged with radionuclides are opening studies on new fields of receptor defects both at the receptor site and beyond. Common disorders such as diabetes mellitus, hyperthyroidism and acromegaly have been the first to benefit. Tracer methods to study secretory and clearance rates and the size of metabolic pools are mainly based on the use of radionuclides. DNA probes are useful in unravelling endocrine defects at the genome level. Originally using radioiodine but now an increasing number of newly synthesised radiopharmaceuticals, the individual organs are being visualised more specifically. Among these agents are labelled monoclonal antibodies hunting for neoplasias and analogs of adrenal medullary hormones such as metaiodobenzylguanidine (MIBG). From these studies the therapy of endocrine disorders will ultimately benefit.