Kidneys

Kidneys

* The kidneys perform essential functions of removing waste products in the body.
1. Regulation of the water, electrolyte and acid base balance
  1. Excretions of products of protein and nucleic acid metabolism - urea, creatinine and uric acid
    1. Also an endocrine organ producing a number of hormones
      1. Argine vasopressin AVP acts to influence water balance
      2. contributes to the glucose supply in fasting state during gluconeogenesis
Serum creatinine
1. Creatinine is a waste product that forms when creatine breaks down. Creatine is a substance found in muscle and is produced as the result of normal muscle metabolism
2. creatinine clearance
  1. The amount of blood the kidneys can make creatinine-free each minute is called the creatinine clearance. In a healthy adult this is 140mL/min however this varies with body size
  2. The higher the blood creatinine level, the lower the estimated GFR and creatinine clearance.
  3. Volume of plasma = U x V / P V is volume if urine in litres collected 24 hours U= urine creatinine concentration P= plasma concentration of creatinine
  4. Certain drugs, including spironolactone, cimetidine, fenofibrate, trimethoprim and amiloride, decrease creatinine secretion and thus can reduce creatinine clearance
    1. Rhabdomyolysis is the breakdown of muscle tissue that leads to the release of muscle fiber contents into the blood.
3. Estimated GFR
  1. where [sCr] = serum creatinine concentration (µmol/L) and age is measured in years. This formula is for white males: the result should be multiplied by 0.742 for females and by 1.21 for African Caribbean people
  2. Several formulae have been derived from the Modification of Diet in Renal Disease (MDRD) study. The ‘four-variable’ formula
4. Limitations
  1. Eating meat can raise Creatinine levels
  2. Amputes have less creatinine
Urea
1. Urea is a waste product formed from the breakdown of proteins. Urea is usually passed out in the urine. A high blood level of urea URAEMIA indicates that the kidneys may not be working properly, or that you are dehydrated
2. Less reliable indicator of GFR than creatinine
3. there are many things besides kidney disease that can affect urea levels such as decreased blood flow to the kidneys as in congestive heart failure, shock, stress, recent heart attack or severe burns; bleeding from the gastrointestinal tract; conditions that cause obstruction of urine flow; or dehydration. Eating high levels of protein can also affect urea
Sodium
1. The body uses sodium to control blood pressure and blood volume. Sodium is also needed for your muscles and nerves to work properly.
2. hypernatraemia- High levels- a rise in serum sodium concentration to a value exceeding 145 mmol/L
  1. Serum sodium concentration, and hence osmolality, is normally kept from rising significantly by the release of antidiuretic hormone (ADH) or vasopressin which limits water losses, and the stimulation of thirst which increases water intake
  2. Salt works on your kidneys to make your body hold on to more water. This extra stored water raises your blood pressure and puts strain on your kidneys, arteries, heart and brain
3. hyponatraemia- Hyponatraemia represents a relative excess of water in relation to sodium
  1. A low sodium level in the blood may result from excess water or fluid in the body, diluting the normal amount of sodium so that the concentration appears low. This type of hyponatraemia can be the result of chronic conditions such as kidney failure (when excess fluid cannot be efficiently excreted) and congestive heart failure, in which excess fluid accumulates in the body
  2. Lead to odema
  3. Sodium reabsorbed in the proximal tuble 65% and 25% in loop of henle
Potassium
1. Potassium is crucial to heart function and plays a key role in skeletal and smooth muscle contraction, making it important for normal digestive and muscular function
2. Hypokalemia
  1. Most cases are the result of either diuretic consumption or loss of gastrointestinal (GI) fluids through persistent vomiting, chronic diarrhoea or laxative abuse. With vomiting, the cause is not mainly direct loss of potassium but that of chloride causing high levels of aldosterone which inhibits potassium reabsorption from the kidney tubules
3. Hyperkalaemia
  1. may occur if your kidneys do not work properly and cannot remove potassium from your body or if your body's cells release too much potassium.
  2. Breakdown of red blood cells, called hemolysis Breakdown of muscle tissue, called rhabdomyolysis Burns, trauma, or other tissue injury Uncontrolled diabetes Conditions that can affect the kidney's ability to remove potassium from the body include: Hormonal disorders Lupus Kidney failure Other kidney diseases
Calcium
1. It’s essential for blood clotting. It stabilizes blood pressure. It contributes to normal brain function. It’s critical for communicating essential information among cells.
2. Hypercalcemia
  1. Parathyroid glands (four small glands) are located near the thyroid gland in the neck and regulate parathyroid hormone which in turn regulates calcium in the blood. When at least one of your parathyroid glands becomes overly active, the condition is called hyperparathyroidism. This is the leading cause of hypercalcemia
  2. Cancers e.g. multiple myloma
  3. Kidney stones build up of calcium
  4. Some types of drugs, such as thiazide diuretics, can cause hypercalcemia because less calcium is excreted and more retained in the body. Other drugs, such as lithium, cause more PTH to be released
3. Hypocalcemia
  1. acute pancreatitis, kidney failure, phosphate or calcium infusion, hypoparathyroidism (most often after surgery), diabetes of the mother (in the case of infants), spreading cancer, and certain drugs
Posphate
1. he body needs phosphorus to build and repair bones and teeth, help nerves function, and make muscles contract
2. Hyperphosphatemia
3. Hyperphosphatemia
Fanconi syndrome (also known as Fanconi's syndrome) is a disease of the proximal renal tubules[1] of the kidney in which glucose, amino acids, uric acid, phosphate and bicarbonate are passed into the urine, instead of being reabsorbed
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