Acromegaly, Gigantism, & Short Stature PDF

ACROMEGALY AND GIGANTISM  Endocrinology & growth The regulation of growth hormone (GH) secretion. [+] Stimulation; [−] inhibition. Citation: CHAPTER 22 The Endocrine System, Laposata M. Laposata's Laboratory Medicine: Diagnosis of Disease in the Clinical Laboratory, 3...

ACROMEGALY AND GIGANTISM  Endocrinology & growth The regulation of growth hormone (GH) secretion. [+] Stimulation; [−] inhibition. Citation: CHAPTER 22 The Endocrine System, Laposata M. Laposata's Laboratory Medicine: Diagnosis of Disease in the Clinical Laboratory, 3e; 2019. Available at: https://accessmedicine.mhmedical.com/content.aspx?sectionid=201364139&bookid=2503&Resultclick=2 Accessed: August 19, 2021 Copyright © 2021 McGraw-Hill Education. All rights reserved Acromegaly Results from the hypersecretion of growth hormone Annual Incidence: 10/1 million people (rare) Average age of diagnosis is 40 to 45 Often missed for years due to insidious presentation Gigantism: GH excess that occurs before fusion of the epiphyseal growth plates in a child or adolescent  Acromegaly Etiology Most common cause = pituitary adenoma Somatotroph (growth hormone [GH]-secreting) adenoma Account for approximately 1/3rd of all hormone-secreting pituitary adenomas Rarely, (200 ng/mL Hypogonadism (secondary to co-secretion of prolactin or from mass effect): Women: Menstrual dysfunction, with or without galactorrhea, hot flashes, vaginal atrophy Men: Erectile dysfunction, loss of libido, decreased facial hair growth, decrease in testicular volume Secondary hypothyroidism sometimes occurs; hypoadrenalism is unusual Acromegaly Complications Metabolic — Uncontrolled acromegaly is associated with hyperinsulinism Insulin resistance about 50% of patients→ will cause T2DM Hypertriglyceridemia or hypercalciuria Hyperphosphatemia (70%) Due to direct stimulation of renal tubular phosphate reabsorption Acromegaly Complications Visceral Organ Enlargement: Thyroid enlargement may be diffuse or multinodular Cardiovascular Disease: Hypertension (50% of patients), left ventricular hypertrophy, & cardiomyopathy, valvular disease, arrhythmia Death from acromegaly is primarily due to cardiovascular disease Obstructive Sleep Apnea Acromegaly Complications Conflicting evidence suggests that acromegaly is associated with an increased risk of colonic neoplasia Increased risk of adenomatous colonic polyps in patients with acromegaly Increased prevalence of colonic diverticula  Acromegaly Complications Increased risk of cancer: Colon tumors Adenocarcinomas of stomach Esophageal Melanoma Thyroid cancers Nonspecific symptoms — Fatigue & weakness can be prominent symptoms Acromegaly Diagnosis ↑GH Varies with sleep, food intake, & exercise The best single test for the diagnosis of acromegaly= measurement of serum insulin-like growth factor-1 (IGF-1) IGF-1 concentrations do not vary & reflect GH secretion during the preceding day or longer An elevated serum IGF-1 concentration in a patient with typical clinical manifestations of acromegaly confirms the diagnosis of acromegaly  Acromegaly Diagnosis If the serum IGF-1 concentration is equivocal → glucose suppression test Diagnosis of acromegaly is confirmed by demonstrating the failure of GH suppression to