Pituitary Dwarfism

Deficiency in growth hormone that is either isolated or combined with deficiency in other anterior pituitary hormones.

There are four types of pituitary dwarfism: Pituitary Dwarfism type I: (Primordial Dwarfism; Sexual Ateleiotic Dwarfism; Isolated Autosomal Recessive Growth Hormone Deficiency Dwarfism) is characterized by sexual ateleiotic dwarfism, hypoglycemia, puppet (baby doll) facies, antibodies to administered growth hormone. It is inherited as an autosomal recessive trait.

Pituitary Dwarfism type II: (Laron Dwarfism type I; Laron Syndrome; Growth Hormone Receptor Deficiency Syndrome; Growth Hormone Insensitivity Syndrome) is characterized by marked short stature and short limbs. Clinical hyposomatotropism. However, the body proportions in childhood appear normal. In the adult period, the body proportions are childlike. Interestingly, the body proportions are more marked in the stature than head size. There is increased resistance to the action of growth hormone (GH). Occasionally blue sclerae. Other clinical features include hip degeneration, limited elbow extensibility, acrohypoplasia, and high-pitched voice. Distorted sex ratio (19F:2M) in Loja province Ecuador cases. Markedly advanced osseous maturation for height and age. It is believed to be cause by a failure to generate somatomedin (or insulin-like growth factor, IGF1) in response to GH. Normal or increased levels of GH. Growth hormone receptor (GHR) defect. Low IGF1 despite normal or increased levels of GH. It is inherited as an autosomal recessive trait.

Pituitary Dwarfism type III: (Panhypopituitarism; Ateliotic Dwarfism with Hypogonadism Syndrome; Hanhart Dwarfism; Rigid Cervical Spine Pituitary Hormone Deficiency Syndrome) is characterized by ateliotic dwarfism, multiple endocrine anomalies (hypothyroidism, hypoadrenalism, hypogonadism and panhypopituitarism), neonatal hypoglycemia, and hypoglycemic seizures. Laboratory investigation reveals the presence of sequential loss of anterior pituitary tropic hormones, GH, gonadotropin, thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), and prolactin deficiency. It is inherited as an autosomal recessive trait.

Pituitary Dwarfism type IV: (Normal Immunoreactive Growth Hormone and Low Somatomedin Pituitary Dwarfism Syndrome; Biodefective Growth Hormone Syndrome; Kowarski Syndrome) is characterized by growth retardation, pituitary dwarfism, and delayed bone age. Normal immunoreactive GH after stimulation, low somatomedin, exogenous human GH responsive, structural abnormality of GH molecule confirmed the diagnosis. It is inherited as an autosomal recessive trait.

The incidence of types I and II pituitary dwarfism are not known, but panhypopituitary dwarfism is not excessively rare; there are probably 7000 to 10,000 cases in the United States alone.

Both types I and II pituitary dwarfism are inherited autosomal recessively. The human GHR gene is mapped to 5p13.1-p12. Many cases of panhypopituitary dwarfism are caused by craniopharyngioma and other nongenetic causes. The form inherited as an autosomal recessive or X-linked form is rare.

There is a defect in the gene encoding GH resulting in either biodefective GH, GH deficiency, or GHR deficiency. The isolated GH deficiency in type I dwarfism may be the result of a defect in hypothalamic releasing factor. Laron syndrome is caused by target resistance to the action of GH.

Laron type I syndrome is characterized by (a) clinical signs of GH deficiency (short stature, decreased growth velocity and delayed bone age) despite normal or increased plasma GH levels; (b) low IGF1 levels that are unresponsive to exogenous GH; and often by (c) low GH-binding protein levels.

In types I and II, dwarfism with child-like body proportions and small facies in adult period. In types III and IV, the clinical picture depends on the age of loss of pituitary function. In type I pituitary dwarfism, the dwarfism is more extreme than in other cases, hypoglycemia is a conspicuous feature, and the puppet facies (“baby doll facies”) is exaggerated. In addition, development of anti-GH antibodies occurs when exogenous GH is administered. Laron syndrome has a very similar clinical appearance to those with isolated GH deficiency. Laron syndrome is characterized by clinical hyposomatotropism manifested by short stature, delayed bone age, and, occasionally, blue sclerae, and hip degeneration. Instability of the odonto-atlantoid joint has been described. The stimulation of growth by IGF1 treatment is prescribed, although the long-term effects have not been documented. Delayed puberty and high-pitched voice. In panhypopituitary dwarfism, the patients show sequential loss of anterior pituitary tropic hormones usually in the order of GH, gonadotropin, TSH, and adrenocorticotropic hormone (hypoglycemia, hypogonadism, hypothyroidism, hypoadrenalism).

Avoid prolonged preoperative fasting because these patients are prone to hypoglycemia. Blood sugar levels should be monitored regularly. In patients with panhypopituitary dwarfism, thyroid function should be assessed both clinically and biochemically, and any replacement thyroxine therapy optimized prior to elective surgery. Ensure supplementation of mineralocorticoids and glucocorticoids in the presence of hypoadrenalism. In a case of Laron syndrome, check odonto-atlantoid joint by cervical radiograph.

Pituitary dwarfism patients have a proportionately smaller airway without anatomic difficulties. A range of laryngoscope blades, handles, and airways appropriate for a smaller patient should be available. The endotracheal tube size could be estimated from the patient's height, in a fashion similar to that of a child of normal height.

Hypothyroidism may cause increased sensitivity to centrally depressant drugs such as opioids, volatile anesthetics, and intravenous anesthetic agents. It may also reduce drug metabolism and excretion.