Hypophosphatemia Flashcards
Q: What does hypophosphatemia mean?
A: Hypophosphatemia means having a low phosphate level in the blood, typically below 2.5 mg/dL.
Q: What is the chemical composition of phosphate?
A: Phosphate is made up of one central phosphorus atom surrounded by four oxygen atoms in a tetrahedral arrangement and has a charge of minus 3 (PO4^3-).
Q: Where is most of the body’s phosphate stored?
A: About 85% of the body’s phosphate is stored in the bones as hydroxyapatite.
Q: What is the role of phosphate in the body?
A: Phosphate is crucial for phosphorylation, ATP production, DNA and RNA backbone formation, and cellular signaling molecules like cAMP.
Q: How is phosphate related to calcium in the body?
A: Phosphate levels are heavily tied to ionized calcium levels, as they often bind together in the bones and are regulated by parathyroid hormone (PTH).
Q: What role does parathyroid hormone (PTH) play in phosphate and calcium regulation?
A: PTH stimulates bone resorption to release calcium and phosphate, inhibits phosphate reabsorption in the kidneys, and increases calcium reabsorption.
Q: What are the main causes of hypophosphatemia?
A: Excess phosphate loss, decreased absorption, inadequate dietary intake, or intracellular shift of phosphate can cause hypophosphatemia.
Q: How can primary hyperparathyroidism lead to hypophosphatemia?
A: It results in excess PTH, which increases phosphate excretion in the urine.
Q: What is Fanconi syndrome?
A: A condition where the proximal convoluted tubule loses its capacity to reabsorb solutes, including phosphate, leading to hypophosphatemia.
Q: How can gastrointestinal factors contribute to hypophosphatemia?
A: Impaired absorption due to substances like alcohol or certain medications can cause phosphate to be excreted rather than absorbed.
Q: What is refeeding syndrome?
A: A condition where sudden refeeding after malnutrition causes a rapid demand for phosphate, leading to hypophosphatemia.
Q: How can diabetes treatment cause hypophosphatemia?
A: Insulin therapy can cause cells to take up phosphate along with glucose, reducing blood phosphate levels.
Q: What is the effect of respiratory alkalosis on phosphate levels?
A: It stimulates glycolysis, increasing cellular demand for phosphate and causing hypophosphatemia.
Q: What are the symptoms of severe hypophosphatemia?
A: Muscle weakness, weak bones or osteomalacia, rhabdomyolysis, and altered mental status.
Q: What mnemonic helps remember symptoms of hypercalcemia due to hypophosphatemia from primary hyperparathyroidism?
A: “Stones, thrones, bones, groans, and psychiatric overtones.”
