Endocrine 2: Disturbances of GH Flashcards
GH Hypofunction diseases
- Pituitary Dwarfism
- Pituitary Infantilism
Causes of Pituitary Dwarfism
- GHRH deficiency
- GH deficiency
- Defect in local IGF-1 secretion by Chondrocytes
- Laron dwarf: defect in GH receptors causing GH insensitivity
- Levi-Lorain: inability to form Somatomedin C/IGF-1 despite normal/high GH
Cause of Laron dwarf
gene mutation causing defect in GH receptor, rending it insensitive to GH
Cause of Levi-Lorain dwarf
heridatery disease causing inability to form IGF-1/Somatomedin despite normal/high levels of GH
difference between pituitary dwarfism & pituitary infantilism
Pituitary infnatilism is associated with hypogonadism (deficincy in gonadotrophic hormones) as well
Manifestations of pituitary dwarfism
- Decrease in size of trunk & extremities
-Normal mentally (may be intelligent)
-Normal sexually
-proportionate body (span= head to symphysis= symphysis to heel)
most common clinical form of dwarfism
Achondroplastic Dwarfism
differential diagnosis of Dwarfism
- Achondroplastic Dwarfism: autosomal dominant gene mutation for FGFR-3 (fibroblast growth factor receptor 3)
- Thyroid dwarfism/Cretin: deficiency of thyroid hormone during infancy
- Pituitary dwarfism
Manifestation of Achondroplastic dwarfism
Disproportion between trunk & extermities
Manifestations of Thyroid Dwarfism/Cretin
- Disproportion between Skeleton & Viceral tissue (tongue, abdomin, etc)
- Mental retardation
- Sexual retardation
GH Hyperfunction diseases
- Giagantism (before adolesence)
- Acromegaly (after adolescence)
Specific skeletal & Tissue growth manefistations of Gigantism
- Symmeterical overgrowth of Bones: normal proportions but taller than normal
- Symmetrical overgrowth of Soft tissue: Muscles are strong at first but then become very weak due to stretch
Specific skeletal & Tissue growth manefistations of Acromegaly
- No linear growth of long bones
- All bones of the body grow in thickness
- Growth of Skull flat bones:
- prognathism (protrusion of lower jaw)
- Prominent supercilliary ridges - Bending of the spine (kyphosis) due to overweight
- Bulldog face (overgrowth of some facial skin)
- Overgrowth of soft tissue (muscles & vicera)
General Manifestation in both Gigantism & Acromegaly
- Increased 4-hyrdoxy-proline secretion in urine (sign of excess soft tissue enlargement
- Hyperglycemia (10% of patients develop DM)
- Glucosuria
- Enlarged thyroid gland (goiters)
- May produce Bitemporal Hemianopia (visual field loss)
- Gynocomastia in males, Galactorrhea in females
- Hypogonadism (pressure on gonadotrophic cells)
- (ends by) panhypopituitarism= Destruction of all pituitary gland cells
Explain why Acromegaly/ Gaigantism may cause Bitemporal hemianopia
- Due to enlargment of the pituitary gland
- Causing pressue onto optic chiasma
