KPD-IGM-Medicine-CPAT-Endocrine-Function-Lecture-STUDENTS-HANDOUT PDF

9/2/24 Learning Objectives: 1. Review the physiology of the hormones prod...

9/2/24 Learning Objectives: 1. Review the physiology of the hormones produced by the pituitary, thyroid and adrenal glands. 2. Learn the different laboratory tests utilized for the diagnosis of the EVALUATION OF common endocrine disorders. ENDOCRINE FUNCTION 3. Interpret the results of above tests for appropriate diagnosis and management of patients with these disorders. Kamille Faye P. Dela Cruz, RPh, MD, DPSP and Iryll Clarence G. Matabang, RMT, MD, DPSP 4. Understand the general principles of stimulation and suppression Department of Pathology, College of Medicine tests relevant for specific endocrine disorders. Our Lady of Fatima University – Valenzuela City 5. Apply knowledge learned for rational use of these tests. 1 2 OUTLINE Introduction to Endocrine System Pituitary Function THE ENDOCRINE SYSTEM Thyroid Function Adrenal Function 3 4 Endocrine System Endocrine System ´ The function of the endocrine system is to secrete hormones into ´ Endocrine hormones: released by glands or specialized cells into the bloodstream. the circulating blood and influence the function of target cells at another location in the body ´ Hormones: substances that act at sites distant from their place of origin ´Autocrine: act directly upon themselves ´ Neuroendocrine hormones: secreted by neurons into the ´Paracrine: act adjacent to the cells of origin circulating blood and influence the function of target cells at another location in the body ´Intracrine: act within the cells of origin without ever exiting the cells ´ Control metabolism, growth, fertility, electrolyte and water homeostasis, and responses to stress 5 6 1  9/2/24 Endocrine System 7 8 Chemical Structure and Synthesis of Hormones ´ Proteins and polypeptides hormones o Most of the hormones in the body o Proteins: >100 amino acids; Peptides: 250 µg/L 17 18 3  9/2/24 Growth Hormone Growth Hormone ´ Greatest peak: puberty ´ Single-chain polypeptide of 191 amino acids ´ Conditions that stimulate GH secretion: ´ Also called somatotropin ´Major stress (surgery, sepsis) ´ Release is stimulated by growth hormone releasing hormone ´Fasting ´ Synthesized, stored, and secreted by the somatotrophs ´Sex steroids ´ Synthesis and release is inhibited by Somatostatin and IGF-1 ´Chronic malnutrition ´ Stimulates Insulin-like Growth factor-1 (IGF-1) / Somatomedin C ´Uncontrolled Diabetes Mellitus ´ Directly antagonizes the effect of insulin on glucose metabolism, promotes hepatic gluconeogenesis, and stimulates lipolysis ´High-protein meals ´ Serum GH: undetectable for healthy, non-stressed individuals 19 20 Growth Hormone Growth Hormone Excess ACROMEGALY GIGANTISM 21 22 Growth Hormone Excess Growth Hormone Excess ACROMEGALY Testing: ´ Occurs when GH hypersecretion occurs after the fusion of the epiphysis ´ Screening test: randomly collected IGF-1 ´ Pathologic or autonomous GH excess ´ Confirmatory test: oral glucose tolerance test (OGTT) ´ Gigantism – occurs when GH hypersecretion occurs before the ´GH measured at 60 and 120 mins fusion of the long bone epiphysis; tall stature ´Results ´ Bony and soft tissue overgrowth – after epiphyseal closure ´GH undetectable in normal individuals ´prognathism, frontal bossing, and spade-like hands. ´GH rise in patients with acromegaly ´ Treatment: Surgery (tumor ablation) 23 24 4  9/2/24 Growth Hormone Deficiency (GHD) Growth Hormone Deficiency ´ Diagnosed by showing failure of GH to increase adequately in ´ Children: May be genetic or tumors (e.g. response to pharmacologic stimulation craniopharyngioma) ´ Insulin tolerance test (ITT): gold standard ´Growth failure ´Failure of GH to rise above 5 ng/mL in adults and above 10 ´ Adults: complete or even partial failure of the anterior ng/mL in children when glucose drops to 900 µg/24 hours or metanephrine: ´Normetanephrine: >400 ng/L (2.19 nmol/L) > 400 µg/24 hours ´Metanephrine: >236 ng/L (1.20 nmol/L) ´Norepinephrine: >170 µg/24 hours ´Epinephrine: >35 µg/24 hours ´Dopamine: >700 µg/24 hours 85 86 Testing Pheochromocytoma ´ Confirmatory Test ´Clonidine Suppression Test 87 88 REFERENCES: ´ Henry's Clinical Diagnosis and Management by Laboratory Methods 24th Edition ´ Clinical Chemistry Principles, Techniques and Correlations 8th Edition ´ Guyton and Hall Textbook of Medical Physiology 14th Edition THANK YOU! J 89 90 15