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Incidence of hypophosphataemia in patients on parenteral nutrition

By Vanessa Marvin, MSc, MRPharmS, Caroline May, BSc, Callum Livingstone, MRCPath, and Joy Davis, RD

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Vanessa Marvin is principal pharmacist

Caroline May is chief aseptics technician

Callum Livingstone is consultant clinical biochemist

Joy Davis is chief dietitian

all at The Royal Surrey County Hospital, Guildford

Correspondence to vanessa.marvin@royalsurrey.nhs.uk

ABSTRACT

OBJECTIVE — To determine the effect of parenteral nutrition on plasma phosphate levels and to evaluate the incidence of refeeding hypophosphataemia.

SUBJECTS AND SETTING— 250 adult patients started consecutively on parenteral nutrition (PN) were monitored at The Royal Surrey County Hospital, a 530-bed, non-teaching, secondary care trust incorporating medical and surgical care, paediatrics, intensive care, maternity services and a regional cancer centre.

DESIGN — Data on plasma levels of magnesium and phosphate, relevant interventions performed and nutrition outcomes was collated by the Trust Nutrition Support Team.

RESULTS — 36 patients (15 per cent) were found to be hypophosphataemic before commencing PN. 86 patients (34.4 per cent) developed refeeding hypophosphataemia within seven days after commencing PN. It was considered severe (less than 0.5mmol/L phosphate) in 10.8 per cent. Refeeding hypophosphataemia reached a nadir at three days and recovered in over 75 per cent of patients within 10 days without intervention. Cancer patients appear to be at greater risk than non-cancer patients for developing refeeding hypophosphataemia. Plasma magnesium levels did not mimic phosphate levels.

CONCLUSION — Recognition of hypophosphataemia and the development of guidelines for its management in the care of PN patients are important.