Reading a diet question as a physiology question
Every therapeutic diet exists because an organ can no longer handle a particular nutrient load. Failing kidneys cannot excrete sodium, potassium and phosphorus, so those are restricted. A failing heart cannot handle volume, so sodium and fluid are limited. A damaged liver cannot convert ammonia to urea, so protein may be temporarily reduced during encephalopathy. Framing the question this way removes the need to memorise disconnected food lists.
The exam then tests recognition of specific foods within a restriction. High-potassium foods include bananas, oranges, potatoes, tomatoes, avocado, spinach and salt substitutes, which are often overlooked because clients assume they are healthy. High-phosphorus foods include dairy, nuts, beans and cola beverages. High-sodium items include processed meats, canned soups, pickles, cheese and most convenience foods.
A frequent trap is the apparently healthy choice that violates a restriction. For a client on a potassium-restricted renal diet, a baked potato with a salad is a wrong selection despite sounding wholesome. Apples, berries, grapes, cabbage, green beans and rice are the safer low-potassium options that tend to appear as correct answers.
| Condition | Restrict | Encourage | Watch for |
|---|---|---|---|
| Chronic kidney disease | Sodium, potassium, phosphorus, protein | Controlled protein, low-K fruits | Salt substitutes contain potassium |
| Heart failure | Sodium, fluid | Fresh foods, herbs for flavour | Daily weight gain over 1 kg |
| Cirrhosis with encephalopathy | Protein temporarily, sodium | Adequate calories, lactulose | Rising ammonia and confusion |
| Diabetes | Simple sugars, large carb loads | Consistent carbohydrate portions | Hypoglycaemia with missed meals |
| Celiac disease | Wheat, barley, rye | Rice, corn, quinoa, potato | Hidden gluten in sauces |
| Gout | High-purine meats, organ meats | Fluids, low-fat dairy | Alcohol precipitates attacks |
Enteral feeding safety, step by step
Tube feeding items are procedure-safety items. Before any intermittent feed, verify placement using the facility's approved method — pH testing of aspirate and reviewing the documented external tube length, with radiographic confirmation required after initial placement. Auscultating an air bolus is no longer considered reliable and appears as a distractor. Elevate the head of the bed thirty to forty-five degrees during the feed and for at least an hour afterward.
Check gastric residual volume per policy and report high volumes rather than automatically discarding aspirate, since discarding removes electrolytes and gastric contents. Flush the tube with water before and after feeds and medications, give medications separately in liquid form where possible, and never crush enteric-coated or extended-release tablets. Hang time for open-system formula is limited, typically four to eight hours, to prevent bacterial growth.
Complications have signature presentations. Diarrhoea often reflects rapid infusion rate, high osmolality formula or sorbitol-containing medications, and is managed by slowing the rate and reviewing medications rather than immediately stopping nutrition. Aspiration presents with coughing, sudden respiratory distress, decreased saturation and possibly formula in oral secretions; the response is to stop the feed immediately, position the client on their side with the head elevated, suction and notify the provider.
- •Verify placement before every intermittent feed
- •Head of bed 30–45 degrees during and one hour after
- •Flush before and after feeds and medications
- •Aspiration: stop the feed first, then position, suction and report
Parenteral nutrition and refeeding syndrome
Total parenteral nutrition delivers concentrated dextrose, amino acids and lipids through a central line because peripheral veins cannot tolerate the osmolarity. The nursing priorities are strict aseptic technique at the insertion site and tubing changes, frequent blood glucose monitoring because the dextrose load drives hyperglycaemia, and never abruptly stopping the infusion. If a bag is unavailable, hang ten percent dextrose in water to prevent rebound hypoglycaemia and notify the pharmacy.
Because parenteral nutrition lines are high-risk, they are not used for blood draws, medication administration or central venous pressure monitoring unless a dedicated lumen is assigned. New fever, chills or redness at the site suggests catheter-related bloodstream infection and requires prompt reporting, as these clients are already nutritionally compromised.
Refeeding syndrome is the exam's favourite nutrition complication. When a severely malnourished client — chronic alcohol use, anorexia nervosa, prolonged starvation — is fed aggressively, insulin release drives phosphorus, potassium and magnesium into cells. The result is falling serum levels of all three, producing cardiac dysrhythmias, respiratory muscle weakness, confusion and possible death. Prevention means starting slowly, monitoring electrolytes daily and replacing deficits before advancing calories.
- •Central access required for TPN because of high osmolarity
- •Never abruptly discontinue; hang D10W if the bag is delayed
- •Monitor glucose frequently and the site for infection
- •Refeeding syndrome: falling phosphorus, potassium and magnesium
Nutrition assessment, deficiencies and teaching
Nutritional assessment combines history, anthropometrics and labs. Unintentional weight loss of more than five percent in a month or ten percent in six months is significant. Albumin reflects longer-term status but is affected by inflammation and hydration, while prealbumin responds faster and is more useful for tracking short-term change. Poor wound healing, muscle wasting, thinning hair and delayed recovery all point to inadequate intake.
Specific deficiencies produce recognisable pictures the exam reuses. Vitamin B12 deficiency causes macrocytic anaemia with neurological symptoms including paraesthesia and gait disturbance, and clients after gastric surgery need lifelong replacement because intrinsic factor is lost. Iron deficiency causes microcytic anaemia, fatigue and pallor, and supplements are best absorbed with vitamin C on an empty stomach, with the client warned about dark stools and constipation. Thiamine deficiency in chronic alcohol use causes Wernicke encephalopathy with confusion, ataxia and eye movement abnormalities.
Teaching answers reward practicality. Reading food labels for sodium content, using herbs and citrus instead of salt, spacing protein intake through the day for healing, planning consistent carbohydrate intake for diabetes, and increasing fibre gradually with adequate fluid for constipation are all common correct options. Involving the dietitian is appropriate but should supplement rather than replace nursing teaching when the item asks what the nurse should do.
- •Prealbumin tracks short-term nutritional change better than albumin
- •B12 deficiency after gastric surgery requires lifelong replacement
- •Iron with vitamin C improves absorption; expect dark stools
- •Increase fibre gradually and pair it with adequate fluid