The endocrine system includes the pituitary, thyroid, parathyroids, adrenals, hypothalamus, pancreas, ovaries, and testes. Non-endocrine metabolic disorders include problems with fluid and electrolytes and acid-base disorders.
Endocrine and Metabolic Disorders
- Acid-Base Regulation
- Acid-Base Disorders
- Metabolic Acidosis
- Metabolic Alkalosis
- Respiratory Acidosis
- Respiratory Alkalosis
- Overview of Adrenal Function
- Addison Disease
- Secondary Adrenal Insufficiency
- Adrenal Virilism
- Cushing Syndrome
- Primary Aldosteronism
- Secondary Aldosteronism
- Nonfunctional Adrenal Masses
- Diabetes Mellitus (DM)
- Diabetic Ketoacidosis (DKA)
- Nonketotic Hyperosmolar Syndrome (NKHS)
- Alcoholic Ketoacidosis
- Overview of Disorders of Potassium Concentration
- Overview of Disorders of Calcium Concentration
- Overview of Disorders of Phosphate Concentration
- Overview of Disorders of Magnesium Concentration
- Overview of Multiple Endocrine Neoplasias
- Multiple Endocrine Neoplasia, Type 1 (MEN 1)
- Multiple Endocrine Neoplasia, Type 2A (MEN 2A)
- Multiple Endocrine Neoplasia, Type 2B (MEN 2B)
- Introduction to Pituitary Disorders
- Pituitary Lesions
- Generalized Hypopituitarism
- Selective Pituitary Hormone Deficiencies
- Gigantism and Acromegaly
- Central Diabetes Insipidus
- Overview of Porphyrias
- Acute Porphyrias
- Precipitating Factors
- Symptoms and Signs
- Recurrent attacks
- Key Points
- More Information
- Overview of Cutaneous Porphyrias
- Porphyria Cutanea Tarda
- Erythropoietic Protoporphyria and X-linked Protoporphyria
- Overview of Thyroid Function
- Approach to the Patient With a Thyroid Nodule
- Euthyroid Sick Syndrome
- Hashimoto Thyroiditis
- Silent Lymphocytic Thyroiditis
- Subacute Thyroiditis
- Simple Nontoxic Goiter
- Thyroid Cancers
Endocrine and Metabolic Disorders Sections (A-Z)
Acid-Base Regulation and Disorders
Metabolic processes continually produce acid and, to a lesser degree, base. Hydrogen ion (H+) is especially reactive; it can attach to negatively charged proteins and, in high concentrations, alter their overall charge, configuration, and function. To maintain cellular function, the body has elaborate mechanisms that maintain blood H+ concentration within a narrow range—typically 37 to 43 nmol/L (pH 7.43 to 7.37, where pH =−log [H+]) and ideally 40 nmol/L (pH = 7.40). Disturbances of these mechanisms can have serious clinical consequences.
Amyloidosis is any of a group of disparate conditions characterized by extracellular deposition of insoluble fibrils composed of misaggregated proteins. These proteins may accumulate locally, causing relatively few symptoms, or widely, involving multiple organs and causing severe multiorgan failure. Amyloidosis can occur de novo or be secondary to various infectious, inflammatory, or malignant conditions. Diagnosis is by biopsy of affected tissue; the amyloidogenic protein is typed using a variety of immunohistologic and biochemical techniques. Treatment varies with the type of amyloidosis.
Diabetes Mellitus and Disorders of Carbohydrate Metabolism
Hyponatremia is decrease in serum Na concentration < 136 mEq/L caused by an excess of water relative to solute. Common causes include diuretic use, diarrhea, heart failure, and renal disease. Clinical manifestations are primarily neurologic (due to an osmotic shift of water into brain cells causing edema), especially in acute hyponatremia, and include headache, confusion, and stupor; seizures and coma may occur. Diagnosis is by measuring serum Na. Serum and urine electrolytes and osmolality help determine the cause. Treatment involves restricting water intake and promoting its loss, replacing any Na deficit, and correcting the underlying cause.
Lipids are fats that are either absorbed from food or synthesized by the liver. Triglycerides (TGs) and cholesterol contribute most to disease, although all lipids are physiologically important. The primary function of TGs is to store energy in adipocytes and muscle cells; cholesterol is a ubiquitous constituent of cell membranes, steroids, bile acids, and signaling molecules.
Multiple Endocrine Neoplasia (MEN) Syndromes
The pituitary gland controls the functions of peripheral endocrine glands. Pituitary structure and function and relationships between the hypothalamus and the pituitary gland are in Overview of the Endocrine System.
Polyglandular Deficiency Syndromes
Polyglandular deficiency syndromes (PDS) are characterized by sequential or simultaneous deficiencies in the function of several endocrine glands that have a common cause. Etiology is most often autoimmune. Categorization depends on the combination of deficiencies, which fall within 1of 3 types. Diagnosis requires measurement of hormone levels and autoantibodies against affected endocrine glands. Treatment includes replacement of missing or deficient hormones and sometimes immunosuppressants.
Porphyrias result from genetic or acquired deficiencies of enzymes of the heme biosynthetic pathway. These deficiencies allow heme precursors to accumulate, causing toxicity. Porphyrias are defined by the specific enzyme deficiency. Two major clinical manifestations occur: neurovisceral abnormalities (the acute porphyrias) and cutaneous photosensitivity (the cutaneous porphyrias).
Principles of Endocrinology
The endocrine system coordinates functioning between different organs through hormones, which are released into the bloodstream from specific types of cells within endocrine (ductless) glands. Once in circulation, hormones affect function of the target tissue. Some hormones exert an effect on cells of the organ from which they were released (paracrine effect), some even on the same cell type (autocrine effect). Hormones can be peptides of various sizes, steroids (derived from cholesterol), or amino acid derivatives.
The thyroid gland, located in the anterior neck just below the cricoid cartilage, consists of 2 lobes connected by an isthmus. Follicular cells in the gland produce the 2 main thyroid hormones, tetraiodothyronine (thyroxine, T4) and triiodothyronine (T3). These hormones act on cells in virtually every body tissue by combining with nuclear receptors and altering expression of a wide range of gene products. Thyroid hormone is required for normal brain and somatic tissue development in the fetus and neonate, and, in people of all ages, regulates protein, carbohydrate, and fat metabolism.
Also of Interest
The presence of fever in a patient with diabetic ketoacidosis (DKA) results from which of the following?