Learning Objectives Dietary sources Daily Requirements Metabolism Important functions and Deficiency diseases

POTASSIUM Kalium K At. No. 19 Atomic mass 39.0

Potassium Alkali metal Highly reactive, Found in combined state, mostly as Salt.

Requirement (mg) Infants 0 – 0.5 yr = 350 – 925 Children 1 – 3 yr = 550 – 1650 4 – 6 yr = 775 – 2325 7 – 10 yr = 1000 – 3000 11+ = 1525 – 4575 Adult = 1875 – 5600

Human milk contains about 500mg/liter, cow’s milk contains 1365 mg/liter. In infants lean body mass and fecal losses are main determinants of potassium need. Adults can maintain potassium balance with intake as low as infants. Conc. of K+ is low in sweat. Less than 390 mg or 10 mEq/L as compared to sodium 25 – 30 mEq/L.

Dietary sources Chicken , Beef, Beef liver Milk Dried apricots, Peaches Oranges, Banana, All vegetables Broccoli, Tomato

Absorption and Metabolism K is readily absorbed from gut. Very little K is lost in feces Kidneys regulate its secretion under the influence of change in acid-base balance and activity of adrenal cortex. Hyper kalemia not likely to develop even after ingestion or injection of large amount of K, if kidney function is intact.

DIETARY INTAKE AND EXCRETION Daily intake recommended 1.5 … 4.5 grams Average Diet contains 4 … 8.0 grams EXCRETION Excreted mostly in Urine K ions filtered freely in the glomerular filterate 93 % is reabsorbed mostly in the proximal convoluted tubules

Postassium Major cation in ICF, maintains intracellular osmotic pressure. ECF K+ is also an important factor in the skeletal and cardiac muscle activity Contraction and depolarization of heart require potassium

Functions Proper plasma potassium level is essential for : Normal heart function Normal function of skeletal muscle fibers Many enzyme reactions Neuron and muscle activity

Functions Resting membrane potential An important role in the renal tubule, where K+ compete with H+ for exchange with Na+ K + are required for the activity of Na / K- ATPase 98% body potassium is found within cells

Hypokalemia Hypokalemia occurs with: Excessive loss through diarrhea Diabetic Acidosis Certain laxatives and Diuretics

Causes of Hypokalemia When Glucose is converted to glycogen for storage,some K is also stored. Treatment with insulin results in glucose metabolism and storage along with K with-drawl from blood and results in Hypokalemia K replacement should be considered.

Causes of Hypokalemia Chronic wasting disease  K lowering / deficit associated with malnutrition prolonged –ive Nitrogen balance and GE losses. K is stored with nitrogen as muscle protein. Therefore, when breakdown occurs, K also transferred from ICF to ECF and removed by kidney.

Management When rehabilitating from these diseases, diet should contain K+ along with amino acid to ensure adequate retention.

Very high sudden intake 12 gms (250 – 300 mEqt / per sq. m. of body surface area/day or 18 gms for an adult may be fatal because leads to Cardiac arrest.

Signs and symptoms of Hypokalemia Muscle weakness Irritability Paralysis Tachycardia

Hyperkalemia In health, generally not seen K+ ion excretion is efficient However certain clinical conditions lead to hyperkalemia

1. Release from tissues Crushed or infected tissues Intra vascular hemolysis Hematomas Burnt tissues Extensive surgical operations Sudden lysis of tumors

2. Renal Insufficiency Excretion by the distil convoluted Tubules if lower, leads to retention of K+ It is normally the case ,when oligouria is associated

3. Chronic Dehydration & Shock Decreased formation of urine K+ retention

Less K+ secreted by distal tubules into urine 4. Acidosis :H+ ion displaces K+ ion 5. Fever :  temp excessive break down of tissues body proteins 6. Addisons Disease Less K+ secreted by distal tubules into urine 7. I.V. administration

Symptoms Heart ECG changes when plasma K+ reaches 7 mmoles/L T-waves becomes high peaked P-waves disappears QRS-complex broad Wide spread cardiac blocks appear Bradycardia and arrhythmias appear Sudden death may take place

Symptoms 2. Nervous Symptoms Mental confusion Weakness of muscles Tingling of the extremities Treatment: Removal of the primary cause

Hypokalemia Decrease K+ intake Malnutrition Old age K free fluid I.V Starvation Malnutrition Old age K free fluid I.V

Hypokalemia Excessive renal loss a. Diuresis with Frusemide and Thiazide b. Metabolic Alkalosis _ Deficiency of H+ ion Tubular cells More K+ ions undergo change with Na+ Accelerate hypokalemia

Hypokalemia Renal Diseases Excessive loss of K+ ion due to any cause/diuretic Recovery phase of Acute Renal Failure Chronic Pyelonephritis Renal tubular Disorders

Hypokalemia Post operatively e. Hormones Aldosterone  loss of K+ Excess cortisol or overdose of ACTH same effect

Loss from GIT Vomiting Diarrhea GI. Fistulas Excessive use of purgatives

Hypokalemia Excessive Transfer to Cells Glycogenesis Paralysis

Symptoms Anorexia Nausea Muscle weakness Mental depression Respiratory weakness

Symptoms Dyspnea Rapid and irregular pulse Low BP ECG Changes: T-wave inversion Reduce insulin secretion