Pituitary Dwarfism Causes, Symptoms, Diagnosis And Treatment
Pituitary dwarfism or dwarfism is a condition characterized by growth and development disorders caused by insufficient secretion of pituitary Â somatotropeÂ hormone (growth hormone or GH). The condition begins in childhood, but becomes more evidentÂ during puberty. Dwarfism is a condition in which growth is very slowed or delayed. Pituitary dwarfism is a consequence of decreased function of the pituitary glandÂ occurred early in childhood before the ossification of boneÂ cartilages.
Pituitary Dwarfism Causes
Pituitary dwarfism is caused by variousÂ disorders ofÂ the pituitary glandÂ function. The pituitary gland is an organ the size of a pea, located at the base of the brain,Â rests in a small, bony cavity called the Turkish saddle. This gland is divided into three lobes:Â anterior lobeÂ (Adenohypophysis)?, intermediate and posterior (Neurohypophysis). TheÂ adenohypophysis producesÂ theÂ growth hormone (GH), adrenocorticotropinÂ (ACTH), thyroid stimulating hormone (TSH), prolactin, follicle stimulating hormone (FSH), luteinizing hormone (LH).Â The neurohypophysis produceÂ the antidiuretic hormone (vasopressin) and oxytocin.
The growth process starts in the hypothalamus. The hypothalamusÂ provides a dual controlÂ role uponÂ pituitary hormone secretion and autonomic nervous system activity.
The hypothalamus secretes GH-RH (growth hormone –Â releasing hormone) that stimulates growth hormone secretion from theÂ adenohypophysis(GH). When growth hormone is released into the bloodstreamÂ it trigger secretion in the liver of a hormone called insulin-like growth factor-1 (IGF-1). In turn, IGF-1 directly stimulates bone and muscle development, causing growthÂ of theÂ long bones and increased protein synthesis in the muscles. Because growth is a complex phenomenon, it can be slowed or stopped by abnormalities that occur in any part of this process.
There are two types of pituitary dwarfism:
- Pituitary dwarfism due to low adenohypophysisÂ production of hormones. When none of the previous pituitary hormonesÂ areÂ properly produced, endocrine failure isÂ manifested on pituitary hormone dependent lines. It is characterized by slow overall growth, and patientsÂ do not show signs of normalÂ puberty.
- Pituitary dwarfism due to isolated growth hormone deficiency. A common form of dwarfism is caused by deficiency in the production of pituitary growth hormone (GH). Patients are developed proportionally, reach sexual maturity and canÂ reproduce.
What causes pituitary dwarfism?
Pituitary dwarfism may be caused by:
- Genetic mutations – specific investigations are needed in orderÂ to determine the specific genetic mutations that can cause pituitary dwarfism occurrence.
- Trauma (including surgery)Â ofÂ the pituitary gland
- Tumors, trauma or irradiationÂ of theÂ central nervous system
- In most cases the cause of pituitary dwarfism is unknown – idiopathic.
Pituitary Dwarfism Symptoms
ChildrenÂ withÂ pituitary have anÂ abnormal slow growth rate, however the body proportions of children suffering from growth hormone deficiency are normal. Children with a pituitary dwarfismÂ usually have aÂ stature 20-25% lower thanÂ the normalÂ average age stature. Smaller stature is evident from the age of 2-4 years.Â The cranial perimeter in children with growth hormone deficiency is usually normal.
Due to deficient degradation of fat, fat distribution in patientsÂ is much higher than in normalÂ subjectsÂ of the sameÂ age, especially around the waist. Rarely excess fat deposits in the thighs, abdomen or in the mammary glands can occur.
In patientsÂ with pituitary dwarfism,Â protein synthesisÂ is diminished and theÂ muscle mass is proportionallyÂ decreasedÂ than inÂ normal individualsÂ of the same age. Studies show thatÂ in children with pituitary dwarfism,Â the skeletal muscle cells are less numerous than normal. Therefore, muscle strength, which can be measured in older childrenÂ using differentÂ exercise tests, isÂ decreased.
Sexual organs are not sufficiently developed, women have theÂ uterus and vagina ofÂ reduced dimensions, theÂ mammary glands are also underdeveloped. Amenorrhea is also present. In males the testicles are not descended into the scrotum, the penis and scrotumÂ have infant sizes.
Patients may have a normalÂ sexÂ life butÂ reproduction isÂ quite rare and it usually takesÂ place only in isolated deficiency of somatotropin cases.
InadequateÂ degradation of glycogen to glucose can lead toÂ hypoglycemia andÂ seizures in severe and untreated hypoglycemia cases.
IntelligenceÂ is mostly normal, but behaviorÂ remains childish andÂ patients oftenÂ present asthenic type disorders, depression, inferiority complex.
The head and limbsÂ are too small, but proportionate, and this makes the overall appearance of the patient to be harmonic. The face is small, and due to the underdeveloped maxilla and mandible, the smallÂ teethÂ are intercalated. The nose is small, eyes very close to each other, but lively.
Pigmentation spots, freckles and fine wrinklesÂ can be present on the facialÂ skin.Â Due toÂ these wrinkle, the patient getsÂ an appearance of early aging. Hands and feet are small, oftenÂ the skinÂ isÂ cyanotic.
Once puberty has passed, the patient retains the appearance of dwarf, skeleton and muscles remain undeveloped. Because the structure of the infant’s larynx, high-pitched voice in presentÂ also inÂ adults.
In case of craniopharyngioma (a tumor located near the pituitary gland), children can have neurological symptoms such as headaches, vomiting, and vision problems (blurred vision, double vision).
Pituitary Dwarfism Diagnosis
Growth hormone deficiencyÂ is presentÂ at birth, but since the main symptom of pituitary dwarfism isÂ growth at a reduced rate, the disease is not diagnosed until later in childhood. Growth charts by age will help determine a diagnosis. Another diagnostic technique usingÂ x-ray of theÂ hand (fist)Â is usedÂ to determine bone age comparing it with the child’s chronological age. Bone age in children with pituitary dwarfism is usually 2 or more yearsÂ delayedÂ than the actualÂ chronological age. This means that if a child with pituitary dwarfism is 10 years old, his bones will look like those of a child of 8 years.
DosingÂ the growth hormone and IGF-1Â (somatomedinÂ C) in blood is useful for diagnosis. Determination of growth hormone can be performed both in basal conditions and after stimulation (exercise, arginine, glucagon or insulin). Failure or inadequate response to stimulation testsÂ is associated with hypopituitarism.
RadiographyÂ of theÂ “turkish saddle” (bone structure in which the pituitary gland rests)Â or more advanced imaging techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) can help the doctor to highlight the presence ofÂ different tumorsÂ of the pituitary gland .
Pituitary Dwarfism Treatment
To limit growth disorders in children with pituitary dwarfism growth hormone therapy is recommendedÂ that is effective in a number ofÂ as long as the treatment is started duringÂ theÂ growth process.Â Doses areÂ given as daily subcutaneous injection until the child reaches an appropriate height.
To receive treatmentÂ based onÂ growth hormone, a lack of secretion of this hormone that was diagnosed by repeatedÂ blood tests must be evidentiatedÂ .
Dwarfism can be seen in other cases, but that growth hormone is normal:
- Turner syndrome is a genetic disease that affects onlyÂ girls. It is caused by complete or partial absence of a sex chromosome, leading to problems such as low height or reproductive difficulties.
- Children with renal failure, diabetes, tuberculosis, digestive disorders, heart disease and chronic infections
- Prader Willi syndrome is a chromosomal abnormality,Â due to gene deletions of the short arm of chromosome 15 of paternal origin or both chromosomes 15 withÂ maternal origin. Syndrome traits are reduced fetal movements, obesity, hypotonia, mental retardation, short stature, hypogonadism, strabismus, small hands and feet. For these children, administration of growth hormone begins to show encouraging results.
A clear acceleration in the rate of growth of at least 4-7 cm / year indicates a positive response to treatment with growth hormone.
Between theÂ 70’s and 80’sÂ natural growth hormone wasÂ extracted from pituitary glands of cadavers. This hormone has been the source of transmission of a serious disease, Creutzfeld-Jacob. Today, synthetic growth hormone, genetically engineered is used fro treatment
If dwarfism is accompanied by sexual infantilism, treatment with sex hormones is addedÂ – estrogen and progesterone – in girls and testosterone – in boys. Testosterone and its derivatives have the advantage to stimulates protein anabolism, develops muscles massÂ and stature. Testosterone must be administeredÂ with caution in childrenÂ due to itsÂ virilizing effect.
Other drugs that increase endogenous production of growth hormone include: clonidine, arginine, dopamine, propranolol. Anabolic substances such as fluoxinesterone,Â nandroloneÂ and oxandrolone, stimulates protein synthesis, increase cartilage and bone growth.