Low bone mineral density

  • common 
  • many patients are asymptomatic
  • may present with
    • pain (bone, back)
    • atraumatic fractures
    • loss of height
  • monitoring should include
    • serum calcium, phosphorous, magnesium, acetate, 25-hydroxyvitamin D (all may be normal)
    • 24-hour urine collection (calcium, magnesium)
    • baseline DEXA scan, repeated every 1–2 years if abnormal (T-score < -1 diagnostic)
  • adequate intake of calcium and phosphorus essential for prevention
  • aluminum toxicity associated with development of parenteral nutrition-associated bone disease
    • infants at higher risk due to reduced renal function
    • sources of aluminum in parenteral solutions include multivitamins, sodium phosphate, and calcium gluconate
    • serum aluminum level > 100 mcg/dL or urine aluminum/creatinine ratio > 0.3 may indicate contamination of parenteral solution
  • management in parenteral solutions for adults
    • calcium > 15 mEq/day
    • phosphorus > 15 mmol/day
    • magnesium (maintenance)
    • acetate 
    • decrease protein to 1 g/kg/day if nutritionally stable 
  • treatment strategies
    • calcium supplementation 500-1,000 mg/day for adults at risk, total daily intake ≥ 1,500 mg
    • vitamin D supplementation if deficient
    • consider estrogen replacement if postmenopausal 
    • limit steroid use
    • smoking cessation
    • exercise
  • refeeding syndrome
    • severe fluid and electrolyte disturbances caused by rapid nutritional repletion if severely malnourished 
    • characterized by hypophosphatemia, hypokalemia, and hypomagnesemia
    • may be life-threatening if not promptly treated
    • patients at risk should have parenteral nutrition advanced slowly to goal over 3-5 days with close monitoring of relevant tests
    • additional supplementation often required in addition to repletion 
  • hypercapnia
    • excessive CO2 production caused by overfeeding total kcal and dextrose
    • may result in difficulty weaning from mechanical ventilation
    • may be reduced by decreasing caloric load 
  • other deficiencies
    • essential fatty acids (avoid by providing 2%-4% of total kilocalories as linoleic acid and not using lipid-free parenteral solutions for > 2 weeks)
    • selenium 
    • copper 
  • renal complications 
    • hyperoxaluria
    • hypercalciuria
    • renal tubular defects

Prevention of complications

  • inspect solutions at time of compounding and prior to administration and discard if any of 
    • gross particulate contamination
    • discoloration—yellow-brown oil layer or marbling 
  • delay of supplemental parenteral nutrition for 8 days 
    reduces new infections and length of stay compared with immediate initiation in critically ill children in pediatric ICU 
  • ethanol locks associated with decreased risk of catheter-associated bloodstream infection compared with ­heparin locks in children with intestinal failure and chronic ­parenteral nutrition dependence 
  • addition of selenium to parenteral nutrition for ≥ 5 days may reduce risk of new infection in critically 

Dr Drabkin is a senior clinical writer for DynaMed, a database of comprehensive updated summaries covering more than 3,200 clinical topics, and assistant clinical professor of population medicine at Harvard Medical School.


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