How P is affected
kidneys cannot clear P and it accumulates in the blood, so the readings increase
How is vitamin D affected in CKD
- kidneys cannot produce enzyme to convert inactive vitamin D to vitamin D
- vitamin D decreases
How is Ca affected
- vit D receptors in the gut facilitate absorption of Ca –> As vit D decrease, Ca decreases too
- P also binds to Ca ‒> as P increases, free Ca decrease
How PTH is affected in MBD
PTH levels increase because of high P and low Ca
results in bone diease, erythropoeitin resistance
Corrected Ca equation in CKD
Corrected Ca = measured Ca in mmol/L + [0.02 x (40 – serum albumin in g/L)]
Phosphate control (non pharm)
limit dietary P intake to 800-1000mg/day
avoid protein, vegetables (have moderate P), preservatives, dairy, chocolate, cola, grain/wheat products –> switch to white bread/white rice
list the types of P binders
- Ca salts
- CaCO3
- Ca acetate
- non Ca (Sevelamer),
- Lanthanum,
- Al based,
- sucroferric oxyhydroxide (Fe based)
SE of Ca based P binders
hypercalcemia, constipation, loss of appetite,
nausea, vomiting
hypercalcemia bc increased risk of Ca absorption esp in vit D therapy
its also ineffective as a Ca replacement when given alone
SE of sevelamer
constipation, diarrhea, flatulence, indigestion, N/V
tablet also needs to be swallowed whole so thats unslay
and $$$
SE of lanthanum
abdominal pain, diarrhea, nausea, vomiting,
$$$ but its a chewable tablet tho
SE of aluminium P binders
- GI – constipation, diarrhea, GI obstruction
- Phosphate depletion (weakness, mental status changes)
- Aluminum toxicity – dementia, encephalopathy, worsening
anemia, osteomalacia, adynamic bone disease
Used in severe hyperphosphatemia (P > 2.2 mmol/L)
uncontrolled by other binders
Due to risk of toxicity, not recommended to use for > 4 wks
SE of sucroferric oxyhydroxide
Nausea, diarrhea, stool
discoloration, flatulence
but its non Ca, non Al and its chewable
contains iron but not much iron absorption if taken properly, so it doesnt help iron deficiency
patient education on P binders
- pls eat WITH meals and snack
- take 2-3h apart from other drugs –> DDI (P binders may prevent absorption of drugs)
- chewed vs whole tablet
- just dont eat phosphate
- eat a few mouth then eat p binder then eat the rest of the meal
- if u eat before meal, it may cause early satiety
- esp P based drugs eg digoxin, quinolones, warfarin
whats used for vit D deficiency
- calcitriol (active D3)
- Alfacalcidol (synthetic incative vit D)
Dosage form of Calcitriol
oral only
Dosage form of Alfacalcidol
- PO oral capsules, solution
- IV (2mcg/ml)
it also requires activation by 25 - hydroxylase in the liver so pt needs adequate liver function
Names of calcimimetics
- cinnacalcet
- Etecalcetide
SE of cinnacelcet
nausea, vomiting, diarrhea, hypocalcemia (seizures, tetany, muscle cramps)
monitoring of cinnacalcet
- Monitor serum Ca once/week during initiation and dose titration, and every 2 weeks during maintenance
- Monitor PTH 2x/month during initiation and dose titration, and once/month during once PTH is stable
SE of etecalcetide
Nausea, vomiting, diarrhea, hypocalcemia (seizures, QTc prolongation)
Monitoring of etecalcetide
- Monitor: serum Ca within 1 week of initiation/dose adjustment, every 4 weeks after;
- PTH after 4 weeks from initiation/dose adjustment, every 1-3 months thereafter
- initiate etelcalcetide 7 days after last cinacalcet dose (serum Ca must be within normal range)
