Curriculum for Specialty Certificate Examination in Gastroenterology

Countdown to the Examination

Wednesday 3 April 2013

question


An 81-year-old frail man was admitted with a stroke and after eight days of being nil by mouth nasogstric feeding is commenced. Following the commencement of feeding after previous starvation which biochemical abnormality is the most likely cause of his drowsiness?
1-hyperglycaaemia
2-hypermagnesaemia
3-hypernatraemia
4-hypocalcaemia
5-hypophasphataemia

1 comment:

  1. Most feeds contain adequate electrolytes to meet the daily requirements of sodium, potassium, calcium, magnesium, and phosphate, although
    specific requirements can vary enormously.

    Malnourished or metabolically stressed individuals are often salt and water overloaded and excess sodium intake is a frequent problem in patients with renal problems, liver derangement, and cardiac failure. High salt intakes may be needed when intestinal losses are excessive.

    Potassium requirements are often high in malnourished or sick patients and normal plasma levels do not rule out total body depletion. Approximately 6 mmol of potassium is needed per g N for protein synthesis and needs are higher in patients who are postoperative, or on glucose/insulin
    infusions or diuretics. Feeding after a period of starvation
    also leads to high potassium requirements.

    If hypokalaemia is persistent, concurrent hypomagnesaemia
    should be sought as renal and gastrointestinal potassium losses are high in patients with magnesium depletion.

    Calcium levels, adjusted for albumin, may need specific correction and magnesium losses can be enormous in patients with fistulae or high stomas.

    The daily requirement for phosphate is about 0.3 mmol/kg/day but requirements may be much greater when refeeding after starvation.

    BSG guidelines

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