侏儒症患者的症状是生长迟缓，身材矮小，病因是患者幼年时生长激素分泌不足。
巨人症患者的症状是过分生长，身材过高，病因是患者幼年时生长激素分泌过多小儿侏儒症小儿侏儒症的常见病因：1、骨胳系统疾病如软骨营养不良和抗维生素D性佝偻病。
2、染色体异常如先天性愚型（21一三体综合征），猫叫综合症（5号染色体短臂缺失）和先天性卵巢发育不良症。
3、先天性酶的代谢缺陷如粘多糖病和肝糖原累积症。
4、内分泌障碍如垂体性侏儒症，甲状腺功能减退（克汀病）。
5、肾脏疾病如肾小管性酸中毒和范可尼综合征等。
6、家族性矮小症和原发性佚孺症，体质性生长发有延缓或青春期延迟。
7、长期大剂量的肾上腺皮质激素的应用。
垂体性侏儒症系指机体青春期以前腺脑垂体功能减退，生长激素(growth hormone，GH)分泌缺乏或不足，或对生长素不敏感所致的生长发育障碍。
西医病因侏儒症本病可分原发性和继发性两类，原发性者病因未明，多为先天性发育不全或遗传疾病所致，可能为常染色体隐性遗传，呈家族性，以单独生长激素不足为主，男孩较女孩多见，男女比例约为2～4：10。
继发性者可继发于下丘脑-垂体疾病，如肿瘤、感染、颅脑外伤、手术或放疗等因素，直接损伤垂体，或损害下丘脑、或使垂体门脉系中断而致病。
下丘脑一垂体部位肿瘤为继发性垂体性侏儒症的重要原因垂体性侏儒为内分泌性侏儒。
由于先天的(原发的)或后天的(继发的)原因，垂体前叶功能减退，生长激素分泌不足，阻碍身体生长与发育。
垂体性侏儒的主要临床表现有：1)生长迟缓，无青春发动期，成年后有“老小孩”早衰形貌；2)身体矮小，但躯干、四肢和头部比例对称33)骨骺发育迟缓，骨龄低于其实际年龄；4)性器官发育不良，第二性征不发育；5)蝶鞍可以正常(原发性垂体侏儒)或增大(由肿瘤引起的继发性垂体侏儒)；6)实验室检查除生长激素分泌不足外，促性腺激素常缺乏，其他几种垂体前叶促激素的分泌量可正常或偏低、在人的眼睛后方，鼻腔的上端，有一个腺体，叫做脑垂腺，可以分泌生长素，当腺体脑出现肿瘤时，会使巨人症与常人对比生长素分泌过量，形成巨人症，生长激素的功能是促进身体组织之发育与成长，它可促进体内细胞的数目增加及变大，使身体各部分组织之器官变大，是每一个人成长的重要因素，在成长过程的第二性征发育，若是生长激素分泌过量或过少会引起「巨人症」或「侏儒症」。
DEFINITIONGigantism is abnormally large growth due to an excess of growth hormone during childhood, before the bone growth plates have closed.CAUSESThe most common cause of too much growth hormone release is a noncancerous (benign) tumor of the pituitary gland. Other causes include:∙Carney complex 综合征∙McCune-Albright syndrome (MAS) 多发性骨纤维营养不良∙Multiple endocrine neoplasia type 1 (MEN-1) 多发性内分泌瘤1型(MEN-1)∙Neurofibromatosis [,njuərəufi,brəumə'təusis] 多发性神经纤维瘤If excess growth hormone occurs after normal bone growth has stopped, the condition is known as acromegaly.[,ækrəu'meɡəli]内科] 肢端肥大症Gigantism is very rare.SYMPTOMSThe child will grow in height, as well as in the muscles and organs. This excessive growth makes the child extremely large for his or her age.Other symptoms include:∙Delayed puberty青春期延迟∙Double vision or difficulty with side (peripheral) vision∙Frontal bossing and a prominent jaw 颌骨∙Headache∙Increased sweating出汗∙Irregular periods (menstruation)月经失调∙Headache∙Release of breast milk∙Thickening of the facial features∙WeaknessDwarfism侏儒症can result from myriad medical conditions, each with its own separate symptoms and causes. Two disorders, achondroplasia and growth hormone deficiency (also known as pituitary dwarfism), are responsible for the majority of dwarfism cases.AchondroplasiaThe most recognizable and most common form of dwarfism is achondroplasia, which accounts for 70% of dwarfism cases and produces rhizomelic short limbs, increased spinal curvature, and distortion of skull growth. Achondroplasia is an autosomal dominant disorder caused by the presence of a faulty allele in a person's genome. If a pair of achondroplasia alleles are present, the result is fatal. Achondroplasia is a mutation in the fibroblast growth factor receptor gene 3 (FGFR3), which is an inhibitor that regulates bone growth. In cases of achondroplasia, the FGFR3 gene is too aggressive, negatively impacting bone growth.[18]Research by urologist Harry Fisch of the Male Reproductive Center at Columbia Presbyterian Hospital indicates that this defect may be exclusively inherited from the father and becomes increasingly probable with paternal age; specifically males reproducing after 35.[19][edit] Growth hormone deficiencyFurther information: Growth hormone deficiencyGrowth hormone deficiency (GHD) is a medical condition in which the body produces insufficient growth hormone. Growth hormone, also called somatotropin, is a polypeptide hormone which stimulates growth and cell reproduction. If this hormone is lacking, stunted or even halted growth may become apparent. Children with this disorder may grow slowly and puberty may be delayed by several years or indefinitely. Growth hormone deficiency has no single definite cause. It can be caused by mutations of specific genes, damage to the pituitary gland, Turner's syndrome, poor nutrition,[20] or even stress (leading to psychogenic dwarfism).[edit] OtherOther causes of dwarfism include spondyloepiphyseal dysplasia congenita, diastrophic dysplasia, pseudoachondroplasia, hypochondroplasia, Noonan syndrome, primordial dwarfism, Turner syndrome, osteogenesis imperfecta (OI) and hypothyroidism. Severe shortness with skeletal distortion also occurs in several of the Mucopolysaccharidoses and other storage disorders.[21]Serious chronic illnesses may produce dwarfism as a side effect. Harsh environmental conditions, such as malnutrition, may also produce dwarfism. These types of dwarfism are indirect consequences of the generally unhealthy or malnourished condition of the individual, and not by any specific disease. The dwarfism often takes the form of simple short stature, without any deformities. In societies where poor nutrition is widespread, the average height of the population may be reduced below its genetic potential by the lack of proper nutrition.REFERENCESMelmed S, Kleinberg D. Anterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 8.Review D ate: 11/23/2009Review ed By: Ar i S. Eckman, MD, D ivision of Endocrinology and Metabolism, Johns Hopkins School of Medicine, Baltimore, MD. Review provided by VeriMed Healthcare Network. Also review ed by David Zieve, MD, MHA, Medical D irector, A.D.A.M., Inc.A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare C ommission(). 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