A middle aged man noticed that he can no longer fit in his shoes and enlarging of jaw and phalanges. These effects are mediated by?
ANSWER: (C) SomatomedinREF: Harrison's Internal Medicine 17th edition chapter 333Symptoms are suggestive of Acromegaly & GH effects are mediated via Somatomedins. Principal Somatomedins are IGF-I, IGF-II.CLINICAL FEATURES OF ACROMEGALY:Protean manifestations of GH and IGF-I hypersecretion are indolent and often are not clinically diagnosed for 10 years or more. Acral bony overgrowth results in frontal bossing, increased hand and foot size, mandibular enlargement with prognathism, and widened space between the lower incisor teeth.In children and adolescents, initiation of GH hypersecretion prior to epiphyseal long bone closure is associated with development of pituitary gigantism.Soft tissue swelling results in increased heel pad thickness, increased shoe or glove size, ring tightening, characteristic coarse facial features, and a large fleshy nose.Other commonly encountered clinical features include hyperhidrosis, deep and hollow- sounding voice, oily skin, arthropathy, kyphosis, carpal tunnel syndrome, proximal muscle weakness and fatigue, acanthosis nigricans, and skin tags.Generalized visceromegaly occurs, including cardiomegaly, macroglossia, and thyroid gland enlargementThe most significant clinical impact of G H exces s occurs with respect to the cardiovascular system. Coronary heart disease, cardiomyopathy with arrhythmias, left ventricular hypertrophy, decreased diastolic function, and hypertension occur in about 30% of patientsUpper airway obstruction with sleep apnea occurs in more than 60% of patients and isassociated with both soft tissue laryngeal airway obstruction and central sleep dysfunctionDiabetes mellitus develops in 25% of patients with acromegaly, and most patients are intolerant of a glucose load (as GH counteracts the action of insulin).Laboratory InvestigationAge- and gender-matched serum IGF-I (somatomedin) levels are elevated in acromegaly. Consequently, an IGF-I level provides a useful laboratory screening measure when clinical features raise the possibility of acromegaly.Due to the pulsatility of GH secretion, measurement of a single random GH level is not useful for the diagnosis or exclusion of acromegaly and does not correlate with disease severity.The diagnosis of acromegaly is confirmed by demonstrating the failure of GH suppression to <1 ug/L within 1-2 h of an oral glucose load (75 g).
ACTH
TRH
Somatomedin
TGF beta
Genetics