in blood

K - increases

Na - stays the same (less nephrons working but other increase function to compensate) may decrease in end stage with increased water consumption

HCO3 - decreased due to kidneys not being able to replenish them

PO4 - increased (decreased renal excretion, secondary hyperparathyroidism)

Ca2 - decreased

Mg2 - increased

as renal function worsens, vit D decreases → decreased Ca absorption in gut → decrease plasma Ca

PTH (secondary hyperparathyroidism responding)→ bone release of calcium and phosphate →normalise Ca, worsens hyperphosphatemia

occasionally tertiary hyperparathyroidism (overstimulation leading to hypertrophy of glands and unnecessary PTH production)