The keen focus in the study of endocrinology is on the endocrine organs such as the pituitary, adrenals, thyroid, testes, ovaries and pancreas. The most important function of these organs is to secrete hormones and in balanced levels. Human body does not always secrete balanced levels of hormones from these glands and thus a hormonal imbalance occurs. This hormonal imbalance is called as endocrinopathy or endocrinosis, this field of study points out the functioning and how to fix the malfunctioning of any of the endocrine glands. A doctor who specializes in the treatment of endocrine disorders is called an endocrinologist. The doctor specializes in fields such as diabetes (malfunctioning of the pancreas), hyperthyroidism (malfunctioning of the thyroid glands) etc.
After completion of medical school, and after three to four years of internship and residency, further specialization of two or three years is needed. Special branches of endocrinologists:
Thyroid is a gland in the neck overlying the windpipe that regulates the speed of metabolic processes by producing a hormone with the eponymous name thyroxin. Thyroid is an endocrine gland. The thyroid gland which resembles a butterfly, sits astride the trachea. Its secretion - thyroxin, a hormone that regulates the metabolic activity of the body. Too much thyroxin races the metabolism resulting in weight loss, temperature elevation, nervousness and irritability. On the other hand, too little thyroxin slows down the metabolism rate resulting in deep voice, weight gain and water retention. This can result in retardation in physical growth and mental development in children. Both conditions equally affect hair and skin growth, bowel function and menstrual flow.
The thyroid gland is often enlarged whether it is secreting too much hormone, too little or even when it is functioning normally. The thyroid is controlled by the pituitary gland, which secretes Thyroid Stimulating Hormone (TSH) in response to the amount of thyroxin in the blood. TSH increases the amount of thyroxin secreted by the thyroid and also causes the thyroid gland to grow.
Hyperthyroid Goiter : If the amount of TSH is high, the thyroid will both enlarge and secrete too much thyroxin. The result is termed as Hyperthyroidism with a goiter. Graves' disease is the most common form of this disorder.
Euthyroid goiter : If dietary iodine is insufficient, too little thyroxin will be secreted and the pituitary will sense the deficiency and produce more TSH. The thyroid gland will enlarge enough to make sufficient thyroxin.
Hypothyroid goiter: If dietary iodine is severely low, even an enlarged gland will not be able to make enough thyroxin. The gland may keep growing under the influence of TSH, but it may never make enough thyroxin.
An endocrinologist who specializes in the endocrine system can also be consulted for thyroid problems and diseases. Specialists who deal with thyroid problem are called thyroidologists. Thryoidologist and endocrinologist are specially trained doctors who diagnose and treat diseases affecting the thyroid gland. A thyroid specialist continues specialized education focused on thyroid issues after obtaining a Masters degree in medicine. He is qualified and trained to treat conditions that are complex and involve many systems within the body that may be affected due to thyroid imbalance.
A primary care doctor too often misses the diagnosis of a thyroid disease. Sometimes primary care doctors refer patients to a thyroid specialist when there is problem in the endocrine/ hormone systems. Thyroid specialists treat patients with too much or too little thyroid hormone. The thyroid specialist helps the patients to reach a hormone balance by replacing or blocking thyroid hormone. Thyroid specialists also receive special training to manage patients with thyroid growths or thyroid cancer and enlarged thyroid glands. There are times when the services of a thryoidologist or an endocrinologist become absolutely necessary.
The first report of Paraneoplastic syndrome is attributed to a French physician, M Auche, who described the involvement in a peripheral nervous system in cancer patients in 1890. This syndrome is a group of signs and symptoms caused by a substance that is produced by a tumor, or in reaction to a tumor. Paraneoplastic syndrome is defined as a rare disorder triggered by a response to neoplasm of an immune system that is altered. These are clinical syndromes produced by tumor although they occur remotely from the tumor itself.
The symptoms may be of any nature – endocrine, neuromuscular or musculoskeletal, cardiovascular, cutaneous, hematologic, gastrointestinal, renal or miscellaneous. Fever is the most common sign. Other clinical symptoms may be benign but syndromes could be varied; from a malignant carcinoid syndrome to Cushing syndrome. In cancer patients, the central nervous system involvement can be detected and it is a prominent manifestation of cancer.
Because of their protean manifestations, Paraneoplastic syndromes are managed by a medical team of physicians, including medical oncologists, surgeons, radiation oncologists, endocrinologists, hematologists, neurologists and dermatologists.
This syndrome can be due to a number of causes, including hormones or biologically active products, made by tumor, which blocks normal hormone, autoimmunity, immune-complex production and immune suppression. But, this is not caused by the primary tumor itself, or by its metastases, or by compression, infection, nutritional deficiency, or treatment of tumor.
Patients with family history of malignancies are at an increased risk and should be screened for cancer. Paraneoplastic syndromes occur typically among middle-aged to older patients. They are mostly diagnosed with cancers of the lung, breast, ovaries, or lymphatic system or lymphoma.
These symptoms sometimes appear before the diagnosis of a malignancy. When the tumor breaks immune tolerance and begins to attack the normal tissue expressing that protein, this syndrome become prominent.
Types of Paraneoplastic Syndrome
Due to the complexity of this syndrome, its clinical presentations may vary greatly. Hence, Paraneoplastic syndromes is divided into four main categories - endocrine, neurological, mucocutaneous, and hematological syndromes as well as a host of others including rheumatologic, renal, gastrointestinal, Cutaneous and miscellaneous.
Fever, dysgeusia, anorexia, and cachexia are included under miscellaneous category. Fever is associated with lymphomas, acute leukemias, sarcoma and carcinomas.
Rheumatologic syndrome includes polyarthritis, particularly in patients with myelomas, lymphomas, acute leukemia, malignant tumors of the colon, pancreas, prostrate. Scleroderma may precede the evidence of tumor. Widespread form of malignancies of breast, uterus and lung can be observed.
Renal syndrome is characterized by hypokalemic nephropathy, and it occurs in 50% of individuals with ACTH secreting tumors of the lung. Nephrotic syndrome is observed in patients with Hodgkin lymphoma, non Hodgkin lymphoma, malignancies of lung, thyroid, colon, breast, ovary and pancreatic head.
Watery diarrhea and electrolyte imbalance, leads to asthenia, confusion and exhaustion, all characteristic of gastrointestinal syndromes. Severe prostaglandins lead to malabsorption and unavailability of nutrients.
Hematologic syndromes are related to anemia, thrombocytosis, disseminated intravascular coagulation, and leukemoid reactions from several types of cancers. Leukemoid reactions due to immature white blood cells in the blood stream are accompanied by hypereosinophilia and itching.
Cutaneous syndromes are manifested by itching and flushes, alopecia, or hypertrichosis. Blackish pigmentation of the skin usually occurs in patients with metastatic melanomas or pancreatic tumors.
Endocrine syndromes resemble common endocrine disorders. Increased serum and urine cortisol concentrations are common examples of this malignancy.
Neurologic or neuromuscular syndromes relate to cancers and such disorders affect 6% of all patients with cancer. Neuromuscular symptoms mimic common neurological conditions. Myasthenia gravis is a common Paraneoplastic syndrome in patients with thymoma, a malignancy arising from epithelial cells of the thymus.
Paraneoplastic limbic encephalitis is characterized by depression, seizures, irritability and short term memory loss and neurologic symptoms rapidly resemble dementia.
Paraneoplastic cerebellar degeneration causes gait difficulties, dizziness, nausea and diplopia. Sensory neuropathy affects lower and upper extremities and there is progressive memory loss, either symmetric or asymmetric.
As Paraneoplastic syndromes may evolve over weeks to months, they usually stabilize regardless whether the patient's underlying condition improves or worsens. Since this is the first manifestation of cancer, patients should undergo investigation for cancer. Other diagnoses are membrane disease, dementia, encephalopathy, encephalitis, myelitis, anemia, bone marrow failure, chronic fatigue syndrome, mixed connective tissue disease, polycythemia vera and polymyalgia rheumatica among others.
Complete laboratory tests in blood, urine, cerebrospinal fluid, protein electrophoresis, assays for auto antibodies, Endoscopy and imaging studies including whole body scans and FDG-PET scans are prescribed to detect extremely small tumors especially useful for patients with neurologic diseases.
Treatment of Paraneoplastic Syndrome
Treatment for this syndrome varies depending upon the type and location of tumors. The first option of treatment of the underlying tumor is by therapeutic protocols, a combination of surgery, radiation, chemotherapy. Second therapeutic option is for patients with clearly identifiable antibodies by intravenous immunoglobulins, steroids, or plasma exchange.
Surgical treatment is typically directed toward the underlying neoplasm although some Paraneoplastic disorders may resolve rapidly without surgery on the primary tumor.
Bibliography / Reference
Collection of Pages - Last revised Date: March 21, 2019