Vitamin D and Calcium
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T.S. Dharmarajan and Amit Sohagia
Questions and Answers
1. A 68-year-old male from the community with hypertension and hyperlipidemia visits the doctor with complaints
of low back pain, gait problems, and weakness. The
patient had history of falls two times at home, according
to his family. Medications include amlopdipine, simvastatin, aspirin, and ibuprofen for pain. On physical examination, patient has tenderness of spine, ribs, and lower
extremity bones, along with bilateral proximal muscle
weakness. Laboratory studies demonstrate normal hemoglobin and hematocrit, low normal calcium, low normal
phosphorus, normal kidney function, and raised alkaline
phosphatase. X-rays of the spine and pelvis are normal.
The most likely cause of pain and falls is:
(A)Multiple myeloma
(B) Osteoporosis
(C) Primary hyperparathyroidism
(D)Vitamin D deficiency
(E) Bone metastasis
Answer: D
In older adults, Vitamin D deficiency is very common
secondary to ineffective cutaneous synthesis, inadequate
exposure to sun, excessive coverage of skin by clothing
and poor nutritional intake. Musculoskeletal symptoms
including bone pain, muscle weakness, poor gait and balance including falls are the typical manifestations of vitamin D deficiency. Deficiency causes calcium and
phosphorus malabsorption, leading to low calcium and
phosphorus in serum. Elevated parathormone (PTH) levels are a consequence. Vitamin D deficiency may also
cause a decrease in bone mineralization (osteomalacia)
and an increase in alkaline phosphatase. Bone mass is
typically lower in osteoporosis. With myeloma, primary
hyperparathyroidism, and metastatic disease, serum calcium level is usually on the higher side. Osteoporosis is
usually not associated with calcium or alkaline phosphatase abnormalities, unless there is a fracture. There is
a clear indication here for the assessment of 25hydroxy
vitamin D levels.
2. A 62-year-old male was referred by his primary doctor
for evaluation of iron deficiency anemia. Past medical
history includes anemia of long duration, a hip fracture
following a fall, chronic back pain, and Type 1 diabetes
mellitus. The patient denies melena, rectal bleeding or
hematuria. The occult blood test was negative multiple
times. Upper endoscope and colonoscopy a year earlier
for similar reasons did not reveal any evidence for the
site of gastrointestinal blood loss. On examination,
patient appeared thin, with slight muscle wasting;
abdominal examination appeared normal. Laboratory
studies showed: Hemoglobin of 11.4 g/dL, hematocrit
34, BUN 8 mg/dL, creatinine 0.6 mg/dL, ferritin 10 ng/
mL, transferrin saturation 10%, calcium 7.8 mg/dL, albumin 2.8 g/dL, phosphorus 2.8 mg/dL, and Vitamin D
10 ng/mL. CT scan of the abdomen and pelvis showed no
evidence of malignancy but the radiologist reported generalized thinning of pelvic and hip bones. What is the
next step in evaluation?
(A)Begin iron and multivitamin tablets and reassure the
patient
(B) Schedule for capsule endoscopy to evaluate for small
bowel angiodysplasia
(C) Check tissue transglutaminase antibody
(D)Refer to the hematologist for possible bone marrow
evaluation and biopsy
(E) Check intrinsic factor antibody and B12 levels
Answer: C
In a 62-year-old male with iron deficiency anemia without
evidence of gastrointestinal blood loss and the presence
of vitamin D deficiency, evaluation is indicated for malabsorptive disorders including celiac disease. Celiac disease
C.S. Pitchumoni and T.S. Dharmarajan (eds.), Geriatric Gastroenterology,
DOI 10.1007/978-1-4419-1623-5_20, © Springer Science+Business Media, LLC 2012
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is a small bowel disorder characterized by mucosal
inflammation, villous atrophy, and crypt hyperplasia,
occurring upon exposure to dietary gluten; there is demonstrable improvement after withdrawal of gluten from the
diet. The classic form is characterized by fully developed
villous atrophy and features of intestinal malabsorption.
The atypical form is characterized by villous atrophy in
the setting of milder clinical features such as iron
deficiency, osteoporosis, short stature, and/or infertility.
Despite the historical title of “atypical,” this form is the
most common. Option A is inappropriate as iron deficiency
anemia always warrants evaluation for gastrointestinal
blood loss and malignancy. Option B is not appropriate at
this time as multiple stool specimens are negative for
occult blood, although capsule endoscopy can pick up
scalloping and villous atrophy of celiac disease. While
bone marrow can provide an idea of iron stores, it would
not provide an etiology for iron deficiency; B12 deficiency
could be present in celiac disease but would not explain
the laboratory abnormalities described.
3. All of following foods are natural sources of vitamin D
except:
(A)Sea foods, such as salmon, tuna fish, mackerel
(B) Cod liver oil
(C) Dry mushrooms (shiitake)
(D)Egg yolk
(E) Dairy products: milk, yogurt, cheese
Answer: E
Only few foods contain vitamin D. Fatty fishes (such as
salmon, tuna, and mackerel) and cod liver oils are among
the best sources. Small amounts of vitamin D are found in
beef liver, cheese, and egg yolk. Vitamin D in these foods
is primarily in the form of vitamin D3 and its metabolite
25(OH)D3. Some mushrooms provide vitamin D2, with
shiitake mushrooms being a very good source. Dairy products such as milk, cheese, and yogurt contain calcium but
do not contain vitamin D in the natural state, unless they are
fortified. Fortified foods provide most of the vitamin D in
the American diet. Fortification is not applied to every
yogurt and cheese, and so labels have to be carefully scrutinized. Almost all of the US milk supply is fortified with
100 IU/8 oz, as also some brands of almond milk, soy milk,
orange juice, and cereals.
4. Which of the following factors most interferes with calcium
absorption in the small intestine?
(A)Age
(B) Calcium intake with meals
(C) Sodium and protein intake
(D)Components in food such as phytic acid and oxalic
acid
(E) Amount of calcium consumed
T.S. Dharmarajan and A. Sohagia
Answer: C
High intakes of sodium, protein, and even caffeine
increase calcium excretion but do not interfere with
absorption of calcium in the gut. Factors which are responsible for calcium absorption in the gastrointestinal tract
are: amount of calcium consumed (the efficiency of
absorption decreases as calcium intake increases), age
and life stage (absorption decreases to 15–20% in adulthood and continues to decrease as people age; compared
with younger adults, recommended calcium intakes are
higher for females older than 50 years and for both males
and females older than 70 years), vitamin D intake and
status, and components in food (phytic acid and oxalic
acid, found naturally in some plants, which bind to calcium and inhibit absorption). Vegetarians might absorb
less calcium than omnivores because they consume more
plant products containing oxalic and phytic acids. On the
other hand, some vegetarian diets may contain less protein than typical omnivore diets, which may help reduce
calcium excretion. While calcium carbonate is better
absorbed in the presence of acid and with meals, calcium
citrate has reasonable absorption even in the empty stomach or with lower gastric acidity..
5. A 62-year-old patient with history of Crohn’s disease
diagnosed in early adulthood complicated with strictures
and fistulae underwent multiple small bowel surgical procedures and had resection of more than 100 cm of ileum.
He now presents with right-sided flank pain and hematuria.
Currently the patient is taking 6-mercaptopurine, with the
Crohn’s disease in remission. The CT scan confirms
obstructing right renal calculi. The patient underwent
lithotripsy by urologist and now comes to you for dietary
advice to prevent recurrent stones. Which of the following
supplements will most likely lessen his chance of recurrent stone formation?
(A)Zinc
(B) Calcium
(C) Magnesium
(D)Potassium
Answer: B
Calcium oxalate stones are common in patients with
Crohn’s disease who have had ileal resection. More than
100 cm ileal resection may lead to steatorrhea from bile
salt malabsorption. Fat malabsorption tends to increase
oxalate absorption in colon via two mechanisms. (1)
Unabsorbed fatty acids bind calcium leading to a reduction in the formation of insoluble calcium oxalate, which
leaves more oxalate free in the solution for absorption.
(2) Fatty acids and bile salts increase colonic permeability to oxalate. A reduced fat diet and calcium supplementation are recommended to diminish oxalate absorption
20 Vitamin D and Calcium
and prevent hyperoxaluria and nephrolithiasis. Calcium
supplements will bind oxalate in the gut, reducing the
amount of free oxalate available for absorption.
6. Which of the following statements is most accurate
regarding vitamin D?
(A)1,25 Dihydroxy vitamin D formed in the kidney is the
physiologically active form and a reliable measure of
status.
(B) 25 Hydroxy vitamin D is the storage form, but a poor
measure of the vitamin status.
(C) Vitamin D provided in doses of 800 IU daily is safe
and the current recommendation.
(D)Vitamin D is best provided as 500,000 U annually or
50,000 U weekly for 3 months, as compliance
improves with this form of administration.
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Answer: C
Vitamin D as the 25 hydroxy form is the storage form and
the best index of status at the present. While the 1,25
form is physiologically active, it has a short half life and
is labile, with levels poorly suggestive of the status.
Current guidelines from the Institute of Medicine (IOM)
recommend 800 IU daily for adults over age 70 and state
that the upper safe limit is 4,000 U/day. Canadian guidelines recommend a range from 800 to 2,000 U daily.
Large intermittent doses of 500,000 U have been shown
to be associated with falls and fractures. It is likely that
large intermittent doses are metabolized differently from
smaller frequent doses.