Vitamins, Minerals, and Trace Elements

• Phosphate**
  • Target Serum Level: <1.5 mmol/L ⁴
  • Requirement: 600 – 1000 mg/day (19 – 32 mmol/day) ⁵
• Potassium***
  • Target Serum Level: 3.5 – 5.0 mmol/L ⁴
  • Requirement: 1500 – 2000 mg/day (38 – 51 mmol/day) ⁵
• Sodium*
  • Requirement: 1.8 – 2.5 g/day (78 – 108 mmol/day)
  • Equivalent NaCl: 4.6 – 6.4 g/day (78 – 108 mmol/day) ⁵

* Sodium: Sodium and intravascular volume balance is typically maintained by homeostatic mechanisms until eGFR falls below 10 to 15 mL/min/1.73 m². However, patients with mild to moderate CKD, despite relative volume stability, have a reduced ability to respond to high sodium intake, making them prone to fluid overload. Therefore, sodium intake should be limited to a maximum of 2.5 g/day (6.4 g NaCl), unless contraindications exist, such as salt-losing nephropathy.

** Phosphate: Excess phosphate is excreted via urine to maintain a fasting serum concentration of <1.5 mmol/L (4.6 mg/dL) with normal kidney function ⁶. If eGFR falls below 40 mL/min/1.73 m², the likelihood of hyperphosphatemia increases, triggering a cascade of adverse effects ⁴. Common complications include disturbances in mineral and bone metabolism, leading to increased vascular calcification, osteoporosis, or atherosclerosis ⁷, and an increased risk of CKD progression and mortality ⁸. Restriction of oral phosphorus intake to 600 – 1000 mg (19 – 32 mmol) per day or reducing absorption with phosphate binders is typically indicated if fasting serum levels are ≥1.5 mmol/L ⁴.

*** Potassium: About 90% of daily potassium intake is excreted through urine with normal kidney function. The risk of hyperkalemia increases with declining kidney function, posing a higher risk of hypertension, ventricular arrhythmias, and sudden death, particularly when eGFR falls below 15 mL/min/1.73 m²  ⁹. Treatment involves avoiding hyperkalemia-inducing medications and potassium-rich foods.