The Urinary Albumin Excretion Rate Biology Essay

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Urinary albumin excretion rate refers to the amount of protein that is present in the urine. Normally there is not any protein found in the urine due to its large size and inability to pass through the glomeruli and filtration system of the kidneys. The urinary albumin excretion rate can increase due to a condition known as diabetic nephropathy.

Diabetic nephropathy is a disease of the kidneys that occurs over time due to the kidneys inability to properly filter glucose and protein. Normally proteins and glucose are reabsorbed completely by the kidneys. Proteins are reabsorbed completely due to their large size and inability to pass through the small filters of the kidneys. Glucose is usually reabsorbed by the "sodium-dependent glucose transporter", but an overwhelming numbers of glucose, as in someone with diabetes, can be too much for the kidneys to handle and cause leakage of glucose into the urine.

Albumin, a type of protein, can leak into the urine due to glomeruli damage. The kidneys filtration system becomes susceptible to larger proteins, such as albumin, and the kidneys lose their ability to control the passage of larger molecules such as this. Overtime with diabetic nephropathy, the glomeruli become damaged due to obesity, hypertension, or high blood glucose values. This damage to the glomeruli causes the kidneys to leak albumin into the urine thus causing an increase in the urinary albumin excretion rate. Overtime, this leads to end-stage kidney disease and dialysis.

What are the functions of the thyroid hormones in terms of target tissue and target tissue responses?

The three thyroid hormones are T3, T4, and calcitonin. The first thyroid hormone, calcitonin, is derived from the parafollicular cells of the thyroid. Its main function is to inhibit calcium absorption and is involved in the process of bone building by osteoclast inhibition, which in turn inhbitis bone digestion. It also acts on the kidneys by inhibiting tubular reapbsorption of calcium and phosphorus leading to decrease loss in the urine.

The second type of thyroid hormone is Triiodothyronin (T3). This hormone is secreted by the thyroid and effects all body tissue types. This hormone plays a vital role in the regulation of the metabolic rate of all cell types and processes of cellular growth and tissue differentiation.

The third type of thyroid hormone is Thyroxine (T4). This type of hormone is secreted by the thyroid and effects all body tissues except the brains, testes, uterus, spleen, and the thyroid gland. This hormone plays a vital role in energy utilization, growth and development, glucose oxidation, and oxygen consumption.

What are the normal ranges for insulin, glucagon, and glycated hemoglobin?  How is each analyte affected by disease?

The normal range for insulin is 5 - 25 uUnits/mL. Insulin is produced by the beta cells of the pancreas. The first type of disease state that can affect insulin production is diabetes. Type I diabetes affects insulin production by the body's own immune cells attacking the beta cells of the pancrease hereby inhibiting the total production of insulin. Type II diabetes also affects insulin production, but produces some. Basically, there are a variety of disease processes that can affect insulin production and often the patient is required to self-medicate themselves with insulin injections as in diabetes mellitus. There could be a scenario where there also could be excess insulin production. In the disease insulinoma, the beta cells of the pancreas have tumors that increase that production of insulin resulting in hypoglycemia.

The normal range for glucagon is 5- 100 pg/mL. Glucagon is a hormone that is secreted by the pancreas in order to increase the blood concentration of glucose. Glucagon has an important role in the body. When blood glucose levels are low, glucagon acts on the liver to stimulate the release of glycogen, polarizing the glycogen to release glucose. There are certain disease states that can affect how much glucagon is secreted by the body. Certain cancers such as glucagonomas cause an excessive glucagon secretion. The concentration seen in this state is greater than 1,000 pg/mL compared to the normal range. Excess glucagon leads to excess glucose released through the stored glycogenic form in the liver. Also, the amino acid materials in the liver, produce glucose and this in turn can result in diabetes mellitus and other serious disease states.

The normal range for glycated hemoglobin is 4.5 - 8.0%. Glycated hemoglobin is a test that refers to the amount of hemoglobin is bound to glucose. This test is a measure of the average blood glucose concentration or level over the course of the previous 2-3 months (because the average lifespan of red blood cells is 120 days.) There are certain disease states that affect the glycated hemoglobin value. Diabetes mellitus is a particular disease state in which the glycated hemoglobin value can be reasonably high due to the elevated glucose level. There also could be an incidence where there is a lower than normal glycated hemoglobin percentage. This can be seen in individuals who have a disease process that inhibits the red blood cell lifespan to reach the normal 120 days. Diseases such as sickle cell anemia and G6PD deficiency fit this mold.

What specific assays are utilized to assess adrenal gland function?  What are stimulation tests, and what do they assess?

There are a variety of assays used to assess the functionality of the adrenal gland. The first test that is used to assess adrenal gland function is to perform basal hormone measurements of cortisol. Another test that is used to assess adrenal gland function is the overnight metyrapone test. This test is an evaluation of the pituitary gland's ability to produce adrenocorticotrphic hormone in respone to decreased cortisol levels. The next test used to assess adrenal gland function is the corticotrophin-releasing hormone test.

Stimulations tests are tests that are used to measure or confirm a deficiency by injecting a synthetic substance such as , for example, synthetic ACTH, and the amount of substance produced, in this case, aldosterone, by the stimulation is measured. If levels are not sufficient due to simulation, then a certain diagnosis can be made based on the lack of stimulation present.

What formula is used to calcuate free thyroxine index?  What is the diagnostic utility of the FTI in the diagnosis of thyroid disorders?

The formula used to calculate free thyroxine index is done by taking "T3-UP of the previous patient) / (mean T3-UP of the reference population) multiplied by the patient's total T4." 1

Gillespie, Paula, and Neal Lerner. The Allyn and Bacon Guide to Peer Tutoring. Boston: Allyn, 2000. Print.

The diagnostic utility of the free thyroxine index is used to assess thyroid function. In situations where there is a state of hypothyroidism, there is a decrease in the free thyroxine index and there is an increase in the free thyroxine index in states of hyperthyroidism. This is the case because in hypothyroidism, there is a decreased amount of T4 and T3. The opposite is true during hyperthyroidism, where both T3 and T4 are increased thus resulting in an increased free thyroxine index.

Define each of the following diseases/conditions:

Cushing Sydrome

This disease is characterized by hyperadrenalism and relates to excess glucocorticoid production. It also presents with excess mineralcorticoid production which leads to the physical features of retained fluid and also retained sodium. The retained fluid and sodium levels lead to hypertension. Physical manifestations include abnormal fat distribution and a face that appears round. The laboratory tests used to diagnose this condition include "the 24-hour urinary free cortisol, the overnight dexamethasone suppression test, and the plasma or salivary midnight cortisol level." 1

Gillespie, Paula, and Neal Lerner. The Allyn and Bacon Guide to Peer Tutoring. Boston: Allyn, 2000. Print.

Hyperaldosteronism

This condition is present when there is too much (hyper) aldosterone produced by the adrenal glands. This condition causes a decrease in potassium, resulting in hypokalemia, and also causes an increase in bicarbonate ions and pH levels resulting in alkalosis. This condition causes the individual to retain sodium ions (hypernatremia). The common symptoms observed in a patient include an increased blood pressure due to the hypernatremia present. The increased amount of blood pressure in the individual can result in dizzy spells, vision loss, and increasing amounts of headaches. There are certain tests that can be used to establish a diagnosis. These tests include the 24-hour urinary excretion of aldosterone test. This test determines how much aldosterone is lost in the urine after a det that is high in salt. Another test includes the saline suppression test. During this test, a IV with salt solution is given, blood from the patient is taken and levels of aldosterone and renin are then assessed. Diagnostic criteria for this test include high aldosterone and low renin levels.

Addison Disease

This condition is present when there is a deficiency in the hormone cortisol and aldosterone caused by the destruction of the adrenal gland. This condition manifests itself in an autoimmune nature. The main physical symptoms observed in this disease process include abdominal pain, musclular weakness, dizziness upon standing, and abdominal pain. Without proper treatment, the symptoms can get worse such as blood pressure dropping to lower than normal levels, depression can result, and females can have a complete cessation of their menstrual cycle. The tests that are commonly used to diagnose this condition include testing for cortisol deficiency due to the nature of consistently low cortisol levels present in a patient with Addison's disease. Another laboratory test include the ACTH stimulation test. This includes testing cortisol before and after administration of synthetic ACTH to diagnose adrenal insuffiency. BUN tests as well as creatinine tests are also done to monitor the kidneys functionality. Aldosterone levels are also done to determine if the adrenal glands are producing the right amount of aldosterone.

Pheochromocytoma

This condition is present where there are adrenal tumors tumors that secrete the catecholamines: norephinephrine and epinephrine. Common symptoms observed in this condition include tachycardia, and hypertension due to increased levels of catecholamine. Resulting complications from this disease can include stroke, renal deficiency, and sudden death. The laboratory tests used in the diagnosis of this disease include the 24-hour urine metanephrine and urinary VMA.

For each disease listed above, discuss the following:

hormones involved in the disease process

common symptoms observed in each condition

laboratory tests commonly used in the diagnose of each disease

Where and how are carbohydrates metabolized and what is their eventual fate in the body?

What drugs and physiological states affect thyroglobulin?  How does a decrease in thyroglobulin affect circulating thyroid hormones?

Discuss normal thyroid physiology in terms of the synthesis of the three thyroid hormones. Explain the regulation and transport of those hormones.

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