Which result pattern fits osteomalacia due to vitamin D deficiency?

Ca low, PO4 low, PTH high, ALP high

Ca low, PO4 high, PTH high, ALP normal

Ca high, PO4 high, PTH low, ALP normal

Ca high, PO4 low, PTH high, ALP normal

Prealbumin (transthyretin) is preferred over albumin for following a patient's response to nutritional support because it:

Has a half-life of about 2 days

Has a half-life of about 20 days

Vitamins and nutrition

9 ASCP MLS practice questions on Vitamins and nutrition, part of Chemistry. The first 9 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
In a patient with chronic alcohol use, confusion, an unsteady gait and abnormal eye movements most suggest deficiency of:
1. APyridoxine (vitamin B6)
2. BThiamine (vitamin B1)
3. CNiacin (vitamin B3)
4. DRiboflavin (vitamin B2)
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Answer: B · Thiamine (vitamin B1)
This triad is Wernicke encephalopathy, caused by thiamine deficiency. Thiamine pyrophosphate is a coenzyme for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and transketolase, so its lack starves nerve cells of energy. Poor diet and poor absorption make it common in heavy drinkers. Thiamine is given before glucose, because a glucose load can worsen the deficiency.
- A: Pyridoxine deficiency causes neuropathy and sideroblastic anemia, often with isoniazid.
- C: Niacin deficiency causes pellagra: dermatitis, diarrhea and dementia.
- D: Riboflavin deficiency causes cracked lips and a sore tongue.
Question 2 · Medium
Which result pattern fits osteomalacia due to vitamin D deficiency?
1. ACa low, PO4 high, PTH high, ALP normal
2. BCa low, PO4 low, PTH high, ALP high
3. CCa high, PO4 high, PTH low, ALP normal
4. DCa high, PO4 low, PTH high, ALP normal
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Answer: B · Ca low, PO4 low, PTH high, ALP high
Lack of vitamin D reduces calcium absorption, so PTH rises (secondary hyperparathyroidism) and calcium is low or low-normal. PTH makes the kidney lose phosphate, so phosphate falls, and poorly mineralized bone raises ALP from active osteoblasts. A low 25-hydroxyvitamin D confirms the cause. High calcium with low phosphate and high PTH is primary hyperparathyroidism instead.
- A: Low calcium with high phosphate and high PTH fits chronic kidney disease.
- C: High calcium and phosphate with a suppressed PTH fits vitamin D toxicity.
- D: High calcium with high PTH and low phosphate is primary hyperparathyroidism.
Question 3 · Medium
Prealbumin (transthyretin) is preferred over albumin for following a patient's response to nutritional support because it:
1. AHas a half-life of about 2 days
2. BHas a half-life of about 20 days
3. CIs made outside the liver
4. DIs unaffected by inflammation
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Answer: A · Has a half-life of about 2 days
Prealbumin has a half-life of about 2 days, compared with about 20 days for albumin, so it changes within days of a change in protein intake. It is a negative acute-phase protein, so inflammation lowers it whatever the nutritional state, and CRP is often measured alongside it. It is made by the liver and carries thyroxine and retinol-binding protein. Its level rises in kidney failure because the kidney normally clears it.
- B: About 20 days is the half-life of albumin, which is why albumin changes slowly.
- C: Prealbumin is made mainly by the liver.
- D: Prealbumin falls in inflammation because it is a negative acute-phase protein.
Question 4 · Easy
Which vitamins are fat-soluble and therefore most affected by fat malabsorption?
1. AB1, B2, B6 and B12
2. BA, C, D and B12
3. CC, folate and niacin
4. DA, D, E and K
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Answer: D · A, D, E and K
Vitamins A, D, E and K are absorbed with dietary fat in micelles, so they need bile and pancreatic lipase. Cholestasis, pancreatic insufficiency, celiac disease and bariatric surgery can all cause deficiency. In these patients, vitamin K deficiency often shows up first as a prolonged PT. Fat-soluble vitamins are stored in the body, so excess intake can also build up to toxic levels.
- A: The B vitamins are water-soluble.
- B: Vitamin C and B12 are water-soluble, although A and D are fat-soluble.
- C: Vitamin C, folate and niacin are water-soluble.
Question 5 · Medium
Which folate measurement best reflects body stores over the previous few months rather than recent intake?
1. ARandom serum folate
2. BFasting serum folate
3. CUrine folate
4. DRed cell folate
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Answer: D · Red cell folate
Folate is taken up by red cells while they are being made and stays in them for their 120-day life. Red cell folate therefore reflects average folate supply over about 3 to 4 months, while serum folate changes within days and can be normal after a single folate-rich meal. Red cell folate is measured on a whole-blood hemolysate and corrected for the hematocrit. Since US grain fortification, true folate deficiency has become uncommon.
- A: Random serum folate changes quickly with diet.
- B: Fasting reduces the effect of a recent meal, but serum folate still reflects only recent days.
- C: Urine folate reflects recent intake and is not used to judge stores.
Question 6 · Hard
A severely malnourished 30-year-old woman starts tube feeding. On day 3 she is weak and short of breath. Results: phosphorus 0.9 mg/dL [0.29 mmol/L] (reference 2.5-4.5 mg/dL [0.81-1.45 mmol/L]), potassium 2.9 mmol/L, magnesium 1.1 mg/dL [0.45 mmol/L] (reference 1.7-2.4 mg/dL [0.70-0.99 mmol/L]). What is the most likely cause?
1. APrimary hyperparathyroidism
2. BVitamin D toxicity
3. CTumor lysis syndrome
4. DRefeeding syndrome
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Question 7 · Hard
A 66-year-old woman has hemoglobin 8.9 g/dL [89 g/L], MCV 118 fL, hypersegmented neutrophils and numb feet, and has had no B12 treatment. Methylmalonic acid is raised and anti-intrinsic factor antibodies are positive, but serum B12 by a competitive intrinsic factor-binding assay is 520 pg/mL [384 pmol/L] (reference 200-900 pg/mL [148-664 pmol/L]). The most likely explanation is:
1. AA normal B12 that rules out deficiency
2. BAssay interference by anti-IF antibodies
3. CRecent B12 injection before sampling
4. DFolate deficiency, not B12 deficiency
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Question 8 · Medium
In early vitamin D deficiency, serum 1,25-dihydroxyvitamin D is often normal or even raised. Why?
1. AIts half-life in plasma becomes much longer
2. BCalcitonin stimulates kidney conversion
3. CThe liver increases 25-hydroxylation
4. DPTH stimulates kidney 1-alpha-hydroxylase
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Question 9 · Easy
Swollen bleeding gums, corkscrew hairs and tiny bleeds around hair follicles, with a normal PT, point to a lack of which vitamin?
1. AVitamin B12
2. BVitamin C
3. CVitamin A
4. DVitamin K
Answer and explanation in LearnFree account

Vitamins and nutrition

In a patient with chronic alcohol use, confusion, an unsteady gait and abnormal eye movements most suggest deficiency of:

Which result pattern fits osteomalacia due to vitamin D deficiency?

Prealbumin (transthyretin) is preferred over albumin for following a patient's response to nutritional support because it:

Which vitamins are fat-soluble and therefore most affected by fat malabsorption?

Which folate measurement best reflects body stores over the previous few months rather than recent intake?

In early vitamin D deficiency, serum 1,25-dihydroxyvitamin D is often normal or even raised. Why?

Swollen bleeding gums, corkscrew hairs and tiny bleeds around hair follicles, with a normal PT, point to a lack of which vitamin?