Editorial: Hypoalimentation during hyperalimentation

High prevalence of hypophosphataemia amongst patients with infectious diseases. A retrospective study

OBJECTIVES

To describe the prevalence of hypophosphataemia amongst all patients treated during 1993 for infectious diseases. The associations between serum C-reactive protein, serum albumin and white blood cells in blood were studied amongst hypophosphataemic patients. Comparisons were made according to the severity of infection.

DESIGN

A retrospective study of the prevalence of hypophosphataemia, and a case-control study amongst a subgroup of patients.

SETTING

The Department of Infectious Diseases, University Hospital, Umeå, Sweden.

SUBJECTS

For the prevalence study all 967 patients (449 women and 518 men) treated during 1993 were included. In the case-control study, 108 cases, with serum phosphate < or =0.64 mmol L(-1), 216 age-and sex-matched controls with serum phosphate >0.82 mmol L(-1) (men) and >0.86 mmol L(-1) (women), respectively, were included.

RESULTS

In 402 of 967 patients (42%) at least one serum phosphate value was below the reference level. Hypophosphataemia was found in 573 of 1966 blood samples (29%). Severe hypophosphataemia (<0.30 mmol L(-1)) was seen in 1.2% of the patients (0.9% of blood samples). The prevalence of hypophosphataemia was higher amongst women than amongst men. In the case-control study, the serum C-reactive protein and the number of white blood cells was higher amongst the cases compared with the controls (124 vs. 94 mg L(-1) and 11.4 vs. 9.3 cells/L x10(9), respectively). The multiple logistic regression showed a 4-fold higher risk of having low serum phosphate in patients with severe infection, compared with mild infections. None of the other variables (albumin, days of hospital stay or white blood cells in blood) increased the risk for hypophosphataemia.

CONCLUSIONS

The high prevalence of low serum phosphate levels and the increased risk of having low levels in severe infections shown in this study needs further attention.

Drug-induced metabolic disorders and parenteral nutrition in the intensive care unit: a pharmaceutical and metabolic perspective

Since its inception, the field of parenteral nutrition has continued to evolve requiring the expertise of several health care disciplines. This feature has made nutrition support unique among clinical subspecialties. As a member of this team, the pharmacist plays a critical role in the provision of sterile admixtures, compatible nutritional formulations, and cost-effective, therapeutically equivalent strategies. The pharmacist has become more involved in the clinical care of the patient, with particular emphasis on the development of drug-induced metabolic disorders. The multitude of drugs prescribed to hospitalized patients increases the potential for serious metabolic disturbances. This is especially true in the critical care setting where sudden changes in metabolism (e.g., acid-base homeostasis, fluid and electrolyte balance) may result in profoundly negative effects. The critical care setting also represents the most sensitive period of hospitalization where even subtle changes in metabolic homeostasis may assume major clinical significance. Early recognition of offending agents and the institution of appropriate intervention may avert serious iatrogenic diseases. The nutrition support team is in a unique position to address many such disorders through selective manipulation of the various components in the parenteral nutrient admixture. The ability of the pharmacist to recognize the development of drug-induced metabolic disorders lends further support for clinical pharmacy in nutrition support services.

Stimulation of bone formation in vivo by phosphate supplementation

The effect of phosphate supplementation on bone remodeling was assessed in six mature, healthy beagle dogs. The phosphate supplement was given in divided doses orally, daily for 12 weeks in the form of a neutral potassium phosphate preparation. The dose averaged 108 mg P/kg per day, which is double the normal canine phosphorus intake. Bone remodeling was assessed by measurement, at sacrifice, of areas of cortical bone containing different color-coded tetracyclines which had been continuously administered during 12-week control and treatment periods; remodeling was assessed kinetically during the control and treatment periods by replicate studies employing 47Ca intravenously. Both techniques demonstrated that the principal effect of phosphate supplementation was a significant stimulation of bone formation. Within cortical bone, formation was doubled, from an average of 2.7% to 5.3% per year. The major location of new bone deposits was endosteal. Whole skeletal mineral accretion, measured kinetically, increased 45% above an average control value of 0.154 g/day. These studies suggest that, in the adult dog, "normal" plasma phosphate levels are suboptimal for new bone formation. Even with this short duration of administration, phosphate produced microscopic calcification of the renal parenchyma. However, there was no biochemical evidence of renal functional impairment.