Hyperphosphatemia and hypophosphatemia Notes

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Hyperphosphatemia

Hypophosphatemia

NOTES NOTES HYPERPHOSPHATEMIA & HYPOPHOSPHATEMIA GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Phosphate imbalances in blood ▫ Hyperphosphatemia: > 4.5mg/dL ▫ Hypophosphatemia: < 2.5mg/dL ▪ Phosphate intake; absorption through gastrointestinal (GI) tract; kidney excretion; transcellular shift; balance between uptake, release by bone tissue DIAGNOSIS LAB RESULTS ▪ Assess blood phosphate levels TREATMENT ▪ See individual disorders SIGNS & SYMPTOMS ▪ Mild: usually asymptomatic ▪ Severe: may be fatal Figure 115.1 Illustration depicting parathyroid hormone preventing reabsorption of phosphate and promoting reabsorption of calcium. 812 OSMOSIS.ORG
Chapter 115 Hyperphosphatemia & Hypophosphatemia HYPERPHOSPHATEMIA osms.it/hyperphosphatemia 1cm/0.39in below zygomatic process) ▫ Trousseau’s sign (blood pressure cuff occludes brachial artery, pressure on nerve leads to muscle spasm, flexing wrist, metacarpophalangeal joints) ▫ Hyperreflexia ▫ Tingling around mouth ▫ Seizures ▫ Bone pain PATHOLOGY & CAUSES ▪ High phosphate levels in blood > 4.5mg/dL ▪ 70% of individuals with advanced chronic kidney disease ▫ Individuals with chronic kidney disease, hyperphosphatemia → secondary hyperparathyroidism, renal osteodystrophy → bones thin, weak ▪ Risk of metastatic calcification (e.g. kidney stones, nephrocalcinosis) CAUSES ▪ Decreased kidney excretion ▫ Decreased glomerular filtration rate in acute/chronic kidney disease ▫ Hypoparathyroidism ▫ Pseudohypoparathyroidism ▫ Vitamin D intoxication: increased phosphate absorption through Gl tract ▪ Increased phosphate intake ▫ Only acute phosphate load (e.g. too much phosphate-based laxative) ▪ Transcellular shift ▫ Massive cell death (e.g. tumor lysis syndrome, rhabdomyolysis, crush injuries, massive hemolysis— intracellular phosphate released into bloodstream) ▫ Acidosis COMPLICATIONS ▪ Metastatic calcification ▪ Renal calcinosis SIGNS & SYMPTOMS ▪ Mild: asymptomatic ▪ Severe: hypocalcemia ▫ Tetany ▫ Chvostek’s sign (facial muscles twitch after facial nerve lightly finger tapped DIAGNOSIS LAB RESULTS ▪ ▪ ▪ ▪ ▪ ↑ phosphate ↓ calcium ↑ vitamin D ↓ parathyroid hormone ↑ urinary phosphate excretion OTHER DIAGNOSTICS ▪ History, physical examination TREATMENT MEDICATIONS ▪ Decrease phosphate absorbed from GI tract ▫ Phosphate binders (e.g. aluminium salts, calcium carbonate) ▪ Increase phosphate excretion ▫ Healthy kidneys: forced diuresis, intravenous (IV) saline, loop diuretic (furosemide) → overwhelm proximal convoluted tubule of nephron → unable to effectively reabsorb solutes (e.g. phosphates) ▫ Life-threatening hyperphosphatemia: dialysis OTHER INTERVENTIONS ▪ Decrease phosphate intake; avoid highphosphate foods (e.g. dairy, meat, soda) OSMOSIS.ORG 813
HYPOPHOSPHATEMIA osms.it/hypophosphatemia PATHOLOGY & CAUSES ▪ Low phosphate levels in blood < 2.5mg/dL CAUSES ▪ Increased kidney excretion ▫ Primary hyperparathyroidism ▫ Fanconi syndrome: proximal convoluted tubule loses capacity to reabsorb solutes (e.g. phosphates) ▪ Decreased intake, absorption through GI tract ▫ Low intake dietary phosphate (unusual) ▫ Medications impair absorption (e.g. antacids with aluminum/calcium/ magnesium) ▫ Alcohol use disorder → low dietary phosphate intake, vitamin D deficiency ▪ Transcellular shift ▫ Refeeding syndrome in severely malnourished individuals → hypokalemia, cardiac arrhythmias, neurologic problems ▫ Insulin treatment in diabetic ketoacidosis; insulin makes phosphate move from the bloodstream inside the cells ▫ Respiratory alkalosis RISK FACTORS ▪ Alcoholism, diabetes, sepsis COMPLICATIONS ▪ Rhabdomyolysis, kidney damage ▪ Chronic hypophosphatemia ▫ Osteomalacia (adults), rickets (children) 814 OSMOSIS.ORG SIGNS & SYMPTOMS ▪ Mild: asymptomatic ▪ Severe: ▫ Muscle weakness, respiratory/cardiac insufficiency ▫ Altered mental status ▫ Seizures DIAGNOSIS LAB RESULTS ▪ ▪ ▪ ▪ ↓ phosphate ↑ calcium ↓ vitamin D ↑ parathyroid hormone OTHER DIAGNOSTICS ▪ History, physical examination TREATMENT MEDICATIONS ▪ Replenish phosphates ▫ Oral administration, diet alone may suffice ▫ IV for life-threatening hypophosphatemia OTHER INTERVENTIONS ▪ Avoid refeeding syndrome by gradually increasing caloric intake, supplements over several days

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This Osmosis High-Yield Note provides an overview of Hyperphosphatemia and hypophosphatemia essentials. All Osmosis Notes are clearly laid-out and contain striking images, tables, and diagrams to help visual learners understand complex topics quickly and efficiently. Find more information about Hyperphosphatemia and hypophosphatemia by visiting the associated Learn Page.