Severe hypophosphatemia in postoperative patients

Outcomes of patients with post-hepatectomy hypophosphatemia: A narrative review

Phosphate is an essential electrolyte for proper mineralisation of bone, buffering of urine, and diverse cellular actions. Hypophosphatemia (HP) is a clinical spectrum which range from asymptomatic to severe complications such as neuromuscular and pulmonary complications, or even death. Post-hepatectomy HP (PHH) has been reported to be 55.5%-100%. Post-hepatectomy, there is rapid uptake of phosphate and increased mitotic counts to aid in regeneration of residual liver. Concurrently, PHH may be due to increased urinary phosphorous from activation of matrix extracellular phosphoglycoprotein in the injured liver, which decreases phosphate influx into hepatocytes to sustain adenosine triphosphate synthesis. A literature review was performed on PubMed till January 2022. We included 8 studies which reported on impact of PHH on post-operative outcomes. In patients with diseased liver, PHH was reported to have either beneficial or deleterious effects on post-hepatectomy liver failure (PHLF), morbidity and/or mortality in various cohorts. In living donor hepatectomy, PHLF was higher in PHH. Benefits of correction of PHH with reduced post-operative complications have been shown. Correction of PHH should be done based on extent of PHH. Existing studies were however heterogenous; further studies should be conducted to assess PHH on post-operative outcomes with standardized phosphate replacement regimes.

Perioperative Serum Calcium and Phosphorus Levels are Associated with Hospital Costs and Length of Stay after Major Abdominal Surgery

This study aimed to identify an association between serum calcium (Ca) and phosphate (P) levels, tested during the pre- and postoperative period, with hospital costs and length of hospital stay (LOS) of patients who underwent major abdominal surgery. This retrospective cohort study analyzed the medical records of patients who underwent major abdominal surgery. A total of 3893 patients were included in the analysis, and multivariable linear regression analysis was performed. For a 1 mg/dL increase in preoperative Ca, total hospital costs decreased by 3997.9 dollars (coefficient: −3997.9, 95% confidence interval (CI): −4900.5, −30,953; p-value < 0.01), and for a 1 mg/dL increase in postoperative P, total hospital costs decreased by 702.5 dollars (coefficient: −702.5, 95% CI: −1274.5, −67.3; p-value = 0.03). Furthermore, for a 1 mg/dL increase in preoperative Ca, LOS decreased by 2.9 days (coefficient: −2.9, 95% CI: −3.7, −2.1; p-value < 0.01). For a 1 mg/dL increase in postoperative P, LOS decreased by 3.4 days (coefficient: −3.4, 95% CI: −4.2, −2.6; p-value < 0.01). This study suggested preoperative Ca and postoperative P could be useful indicators for the reduction of hospital costs and decrease in LOS from the perspective of enhanced recovery after surgery.

The refeeding syndrome. Importance of phosphorus

Refeeding syndrome (RS) is a complex disease that occurs when nutritional support is initiated after a period of starvation. The hallmark feature is the hypophosphataemia, however other biochemical abnormalities like hypokalaemia, hypomagnesaemia, thiamine deficiency and disorder of sodium and fluid balance are common. The incidence of RS is unknown as no universally accepted definition exists, but it is frequently underdiagnosed. RS is a potentially fatal, but preventable, disorder. The identification of patients at risk is crucial to improve their management. If RS is diagnosed, there is one guideline (NICE 2006) in place to help its treatment (but it is based on low quality of evidence). The aims of this review are: highlight the importance of this problem in malnourished patients, discuss the pathophysiology and clinical characteristics, with a final series of recommendations to reduce the risk of the syndrome and facilitate the treatment.

Refeeding Syndrome and Hypophosphatemia

Hypophosphatemia is a potentially life-threatening complication of reinstating nutrition in a malnourished patient. Refeeding syndrome is a term that refers to various metabolic abnormalities that may complicate carbohydrate administration in subnourished patient populations. Hypophosphatemia is the most well-known, and perhaps most significant, element of the refeeding syndrome and may result in sudden death, rhabdomyolysis, red cell dysfunction, and respiratory insufficiency. This review briefly examines refeeding-induced hypophosphatemia in the hospitalized patient in hopes of making clinicians more aware of this common, but often overlooked, potentially dangerous problem.

Change of serum phosphate level and clinical outcome of hypophosphatemia in massive burn patient

BACKGROUND

Hypophosphatemia is relatively common phenomenon in patients with massive burn injury. Therefore, we check serum phosphate level routinely and try to supply phosphate in a timely manner. The purpose of this study was to investigate the change of the serum phosphate level of early postburn period and the impact of hypophosphatemia on the prognosis of patients.

METHODS

A total of 227 patients with burn injury were reviewed retrospectively. We performed analysis of serum phosphate level within 20 days from burn injury.

RESULTS

Patients' mean (SD) age was 47.0 (14.1) years, and mean (SD) percentage of total body surface area burned were 47.7 (21.9). Severe hypophosphatemia (phosphate < 1.0 mg/dL) was observed in 35 patients (15.8%), and moderate hypophosphatemia (1.0 ≤ phosphate < 2.0 mg/dL) was found in 115 patients (50.6%). Therefore, overall incidence of hypophosphatemia was 66.4%. There was no significant difference in serum phosphate level with survival, total body surface area burned, and mechanical ventilation. Age (odds ratio [OR], 3.180; 95% confidence interval [CI], 1.025-9.871; p = 0.045), total body surface area burned (OR, 20.934; 95% CI, 6.845-64.024; p = 0.000), and mechanical ventilation (OR, 5.581; 95% CI, 2.380-13.085; p = 0.002) were independently associated with mortality. However, serum phosphate level (OR, 0.828; 95% CI, 0.275-2.495; p = 0.737) does not have a statistical significance.

CONCLUSION

Although multiple studies have evaluated the efficacy and safety of phosphate repletion regimens, the effect on mortality and morbidity is not well reported. However, our results show that patients with massive burn injury have high incidence of hypophosphatemia, and hypophosphatemia can result in many complications. Therefore, routine check and supply of phosphate can be suggested in patients with massive burn injury.

LEVEL OF EVIDENCE

Prognostic study, level II.

Isolated C-terminal tail of FGF23 alleviates hypophosphatemia by inhibiting FGF23-FGFR-Klotho complex formation

Fibroblast growth factor (FGF) 23 inhibits renal phosphate reabsorption by activating FGF receptor (FGFR) 1c in a Klotho-dependent fashion. The phosphaturic activity of FGF23 is abrogated by proteolytic cleavage at the RXXR motif that lies at the boundary between the FGF core homology domain and the 72-residue-long C-terminal tail of FGF23. Here, we show that the soluble ectodomains of FGFR1c and Klotho are sufficient to form a ternary complex with FGF23 in vitro. The C-terminal tail of FGF23 mediates binding of FGF23 to a de novo site generated at the composite FGFR1c-Klotho interface. Consistent with this finding, the isolated 72-residue-long C-terminal tail of FGF23 impairs FGF23 signaling by competing with full-length ligand for binding to the binary FGFR-Klotho complex. Injection of the FGF23 C-terminal tail peptide into healthy rats inhibits renal phosphate excretion and induces hyperphosphatemia. In a mouse model of renal phosphate wasting attributable to high FGF23, the FGF23 C-terminal peptide reduces phosphate excretion, leading to an increase in serum phosphate concentration. Our data indicate that proteolytic cleavage at the RXXR motif abrogates FGF23 activity by a dual mechanism: by removing the binding site for the binary FGFR-Klotho complex that resides in the C-terminal region of FGF23, and by generating an endogenous inhibitor of FGF23. We propose that peptides derived from the C-terminal tail of FGF23 or peptidomimetics and small-molecule organomimetics of the C-terminal tail can be used as therapeutics to treat renal phosphate wasting.

Refeeding syndrome in cancer patients

BACKGROUND

Refeeding syndrome (RFS) is a common, yet underappreciated, constellation of electrolyte derangements that typically occurs in acutely ill, malnourished hospitalised patients who are administered glucose solutions or other forms of intravenous or enteral nutrition.

DISCUSSION

The hallmark of RFS is hypophosphataemia, but hypokalaemia and hypomagnesaemia are also common. Patients with various types of malignancies are at-risk for RFS, but very little exists in the oncologic literature about this disorder.

CONCLUSIONS

As RFS can have many adverse metabolic, cardiovascular, haematologic and neurologic complications, practicing oncologist needs to be aware of the pathophysiology, risk factors and clinical manifestations to promptly recognise this important, and potentially fatal, metabolic disorder.

[Prevalence of dysphosphoremia in patients admitted in intensive care unit with an impaired renal function]

OBJECTIVE

To assess the frequency of dysphosphoremia in patients admitted in intensive care unit with an impaired renal function and to determine the associated risks factors. Study design. - Epidemiological prospective study.

PATIENTS AND METHODS

The creatinine clearance and the phosphoremia were measured in 134 consecutive patients admitted in intensive care unit over a six-month period. Patients with chronic renal failure were excluded. Known risk factors for hypophosphoremia in intensive care unit were recorded.

RESULTS

Seventy-nine out of one hundred thirty-four patients (59%) had an impaired renal function (arbitrarily defined by a creatinine clearance < 60 ml/min). The proportion of patients with impaired renal function that where hypo-, normo- (0.8 to 1.2 mmol/l) or hyperphosphoremic was 16, 34 and 50% respectively. Hypophosphoremia was severe (< 0.5 mmol/l) in 5 patients, all with impaired renal function. No risk factors usually associated with hypophosphoremia could be identified.

CONCLUSION

As opposed to chronic renal failure patients who are mainly hyperphosphoremic, patients admitted in intensive care unit with an impaired renal function may present with a normo-, or hypophosphoremia. These dysphosphoremias are sometimes severe. Phosphate status should be promptly determined at admission.

Síndrome de realimentación. Revisión

Refeeding syndrome is a complex clinical picture that encompass all those alterations that can occur as a consequence of the nutritional support (oral, enteral or parenteral) in malnourished patients. Refeeding syndrome is classically characterized by neurological alterations, respiratory symptoms, cardiac arrhythmias and heart failure few days after beginning of refeeding, with life-threatening outcome. Its pathogenesis includes alterations in the corporal fluids, and in some electrolytes, minerals and vitamins. In this article a review of refeeding syndrome pathogenesis and clinical manifestations is carried out, with a final series of recommendations for lowering the risk of this syndrome and for facilitate the early diagnosis and the treatment.

Refeeding Syndrome

Patients admitted to inpatient rehabilitation units commonly have underlying medical disorders and are at risk for poor oral intake and malnutrition, which may be compounded by dysphagia and anorexia. The refeeding syndrome is an underappreciated but clinically important entity characterized by acute electrolyte abnormalities, fluid retention, and dysfunction of various organ systems, which can result in significant morbidity and, occasionally, death. Reinstitution of nutrition by any route in a undernourished patient may lead to acute electrolyte shifts and fluid retention, which are hallmarks of the refeeding syndrome. As such, this article briefly summarizes the clinical manifestations and treatment of refeeding syndrome as it relates to patients admitted to the inpatient rehabilitation unit.

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.