In cyclic PN, what type of calcium balance can be expected?

In cyclic PN, what type of calcium balance can be expected?

• A. A negative calcium balance with an 80% increase in urinary calcium excretion.
• B. A positive calcium balance.
• C. No change in calcium balance.
• D. An indeterminable calcium balance.

Answer: (A)

In parenteral nutrition given in cycles, calcium is delivered in bursts rather than continuously. Since calcium is administered intravenously, the body relies on the kidneys to excrete the excess and on bones to buffer any short-term shifts. The intermittent bursts cause transient spikes in calcium that the kidneys must rapidly filter and excrete, leading to markedly higher urinary calcium losses over each cycle. Over time, these losses tend to outpace the amount of calcium retained or stored, producing a negative calcium balance. The increased urinary excretion can be substantial—around an 80% rise in many observations—so the net effect is negative balance despite ongoing calcium delivery during the infusion periods. In contrast, a positive balance would require net retention of calcium, which is unlikely given the significant renal losses during cyclic infusions. No change or indeterminable balance would not align with the clear pattern of increased urinary calcium loss seen with cyclic administration.

In parenteral nutrition given in cycles, calcium is delivered in bursts rather than continuously. Since calcium is administered intravenously, the body relies on the kidneys to excrete the excess and on bones to buffer any short-term shifts. The intermittent bursts cause transient spikes in calcium that the kidneys must rapidly filter and excrete, leading to markedly higher urinary calcium losses over each cycle. Over time, these losses tend to outpace the amount of calcium retained or stored, producing a negative calcium balance. The increased urinary excretion can be substantial—around an 80% rise in many observations—so the net effect is negative balance despite ongoing calcium delivery during the infusion periods.

In contrast, a positive balance would require net retention of calcium, which is unlikely given the significant renal losses during cyclic infusions. No change or indeterminable balance would not align with the clear pattern of increased urinary calcium loss seen with cyclic administration.