Lec. 3 Inorganic Phosphate PDF - جامعة نينوى

INORGANIC PHOSPHATE ‫عنصر وفير‬ ‫منتشر ع نطاق واسع‬ Phosphorus is an abundant element that is widespread in its distribution. The adult human body contains about 560 g to 850 g of phosphorus. Found everywhere in living cells, phosphate compounds participate in many of...

INORGANIC PHOSPHATE ‫عنصر وفير‬ ‫منتشر ع نطاق واسع‬ Phosphorus is an abundant element that is widespread in its distribution. The adult human body contains about 560 g to 850 g of phosphorus. Found everywhere in living cells, phosphate compounds participate in many of the most important biochemical processes. The genetic materials deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are complex phosphodiesters. Most coenzymes are esters of phosphoric or pyrophosphoric acid. ‫خزانات‬ The most important reservoirs of biochemical energy are ATP, creatine phosphate, and phosphoenolpyruvate. The phosphate in the body can exist in three forms: 1- 85% of which is in your bones and teeth in hydroxyapatite phase Ca₁₀(PO₄)₆(OH)₂. 2- About 15% of phosphorus is located in the cell membrane and the intracellular fluid in the soft tissues in a form of organic phosphate incorporated into phospholipids, nucleic acids and high energy compounds. 3- Serum/plasma contains approximately less than 1% of total phosphate as inorganic phosphate, the fraction measured in routine biochemical analysis. Note: Phosphorus is an element. (P) Phosphate is a compound that contains phosphorus PO₄³⁻ 2022-2021 /‫ جامعة نينوى‬/‫ كلية الطب‬/‫ خالد محمد خضر‬.‫م‬.‫م‬  Biological function of phosphorous It helps with: 1- Bone growth, energy storage, resulting in energy from the formation of adenosine triphosphate (ATP) from adenosine diphosphate (ADP). 2- It is necessary for several enzymatic processes in glycolysis, ammoniagenesis as well as in oxidative phosphorylation. 3- Buffer systems and the phospholipid membrane. ‫لحوم‬ ‫منتجات االلبان‬ Sources: Many foods, especially meats and dairy products, contain phosphorus, so it’s usually easy to get enough of this mineral in your diet. Absorption: Phosphorous is taken in diet its absorption occurs mainly in small intestine. 2022-2021 /‫ جامعة نينوى‬/‫ كلية الطب‬/‫ خالد محمد خضر‬.‫م‬.‫م‬  Clinical significance Serum inorganic phosphate normal range: Adults: 2.4-4.5 mg/dl (0.8-1.5 mmol/l). Children: 4-7 mg/dl (1.29-2.25 mmol/L). ‫أضطرابات‬ ‫توازن‬ Disorders of phosphate homeostasis occur in a wide range of clinical conditions. Both hyper and hypophosphatemia can be caused by cellular shifts of phosphate. The three ‫اختالل وظائف‬ ‫املدخول الغذائي‬ ‫الكلى‬ primary conditions that lead to phosphate dysfunction are dietary intake, GI, and renal status. The kidneys maintain phosphate balance. About 90% of filtered phosphate is reabsorbed (80% in the proximal tubules and 10% in the distal tubules). The remaining 10% is excreted in urine. Inorganic phosphate plasma level is needed to explain disturbances of calcium metabolism. 2022-2021 /‫ جامعة نينوى‬/‫ كلية الطب‬/‫ خالد محمد خضر‬.‫م‬.‫م‬  Factors that control blood phosphate level 1- Parathyroid hormone (PTH) decreases phosphate reabsorption at the proximal tubule, leading to low levels of phosphate in the blood. 2- Fibroblast growth factor 23 (FGF23) (is a hormone produce by osteocyte in bone) reduces phosphate reabsorption by the kidneys, leading to low levels of phosphate in the blood. 3- Vit D helps the small intestine and the kidney to reabsorb phosphate back into the bloodstream, leading to increase levels of phosphate in the blood. Hormonal regulation of calcium and phosphorus. Serum calcium and phosphorus balance is maintained by a tight interplay between parathyroid hormone (PTH), vitamin D and fibroblast growth factor 23 (FGF23). 2022-2021 /‫ جامعة نينوى‬/‫ كلية الطب‬/‫ خالد محمد خضر‬.‫م‬.‫م‬  Hyperphosphatemia Hyperphosphatemia is an electrolyte disorder in which there is an elevated level of phosphate in the blood. Major causes:  Hypoparathyroidism.  Renal failure.  Acute metabolic acidosis.  Addison’s disease. Hyperphosphatemia is a major risk factor for death, cardiovascular events and vascular calcification among patients with and without kidney disease. Potential mechanisms by which increased phosphate results in adverse outcomes are incompletely understood but current evidence suggests a direct effect of phosphate on vascular calcification. Putative Mechanisms Linking Hyperphosphatemia and Cardiovascular Disease 2022-2021 /‫ جامعة نينوى‬/‫ كلية الطب‬/‫ خالد محمد خضر‬.‫م‬.‫م‬  Hypophosphatemia Is an electrolyte disorder in which there is a low level of phosphate in the blood. Symptoms may include weakness, trouble breathing, and loss of appetite..‫قد تشمل األعراض الضعف وصعوبة التنفس وفقدان الشهية‬ Hypophosphatemia can be caused by decreased intestinal absorption, increased renal phosphorus loss, and trans cellular shift of phosphorus from the blood into cells Major causes  Malabsorption. ‫فشل االمتصاص‬  Severe vitamin D deficiency.  Primary hyperparathyroidism.  Renal disorders – losses (Fanconi syndrome) or tumours producing FGF23. Measurement of Serum Inorganic Phosphate Principle In an acid medium, phosphate ions form a phosphomolybdic complex with the ammonium molybdate. The absorbance measured at 340 nm is proportional to the concentration of phosphate ions in the specimen. Blank Standard Test Working reagent (ml) 1 1 1 Standard (µ) ___ 20 ___ Serum (µ) ___ ___ 20 D.W. (µ) 20 ___ ___ Mix well. Incubate 2 min at room temperature. Calculation 𝐴𝑏𝑠. 𝑇𝑒𝑠𝑡 Results = x standard conc. (5 mg/dl) 𝐴𝑏𝑠. (𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑) 2022-2021 /‫ جامعة نينوى‬/‫ كلية الطب‬/‫ خالد محمد خضر‬.‫م‬.‫م‬