1. By
Dr salwa .E. Al-Ansari
Clinical Biochemistry department
j.a. armed forces hospital
Ministry of defense
Kuwait.

2. vitamin D
Fat soluble vitamin
Major two forms :
1. D3
- 25 (OH) D3 (liver)
- 1,25 (OH) D3 (kidney) , active form
- 1.25(OH) T1/2 < 25 (OH)
2. D2 synthesized in plants.

3. Vitamin D roles
1. Bone health
 Osteoporosis
 Rickets
 Muscle weakness
2. Protective role (New!)
 Cancers
 CVD
 Renal diseases
 Autoimmune
 DM
 MS

4. Sources:
1. Diet:
- D2 Plant
- D3 Animal
2. Sun :
e.g. : In Boston, from April
to October at 12 PM EST an
individual with type III
skin, with 25.5% of the body
surface area exposed, would
need to spend 3 to 8 minutes
in the sun to synthesize 400
IU of vitamin D.

6. Skin synthesis varies
 Latitude
 Season
 Clothing
 Age
 Sunscreen use
 Local weather conditions.

7. Serum vt. D varies:
Environmental
Genetic
Nutritional factors (e.g 1/ BMI)
Malabsorption
Hormonal

8. Frank Vt.D deficiency
Serum levels < 10 ng/ml or 25 nmol/l
Vt.D insufficiency
Serum levels 10-30 ng/ml or < 25-75 nmol/l
Previous laws

9. WHO
Below 10 ng /ml : deficiency
Below 20 ng /ml : insufficiency
Research:
Depending on the range : 30 -76 ng/ml ↑
prevalence of vt.D insufficiency

10. New Laws
2007 International workshop on vt.D :
min. range 20 ng/ml.
2010 International osteoporosis
federation :< 30 ng /ml insufficiency.
Endocrine society: vt.D deficiency < 50
nmol/l .

11. US institute of medicine normal range ≥
50 nmol/l
Reference Laboratories raised lower
boundaries. 75-250 nmol/l.

12. Certain studies ; 30 ng / ml optimum :
below↑ PTH : active Ca resorption.
Criticism:
 PTH & vt. D not curve linear .
 PTH variation when vt. D 20-30 ng / ml
 No absolute threshold level.

13.  One study (old women): risk of hip
fracture not ↑ by high dose vt.D
 Switzerland study: women vt.D <20 ng/
ml not related to ↑ risk fracture (5 years
follow up).

14.  No large randomized controlled trials :
vt D supplements → ↓ chronic diseases
other than osteoporosis.
 Storage & re-entry into circulation is
poorly understood.
 Optimum dosage of vt.D :↑100IU → ↑ 3
nmol/l

15.  Observational studies:↑vt.D levels < 150
nmol/l associated with pancreatic cancer.
 Vt.D supplements studies : protective
role depends on dose and stage of life to
be given .

16. Vitamin D assay
Most assays for 25(OH)D cannot
differentiate the two distinct forms, 25(OH)
D2 from 25(OH) D3, so the abbreviation
25(OH)D is used.
Types of assays:
HPLC-Chromatography
RIA
Immunoassay

17. Main Issue:
Reference laboratories ↑ demands for test
by 50 % in 2009 than 2008 ???
Problems:
- Laboratories raised lower boundaries.
- Several assay : accuracy & precision
problems.

18. -[vt. D] changes / seasons, exposure, to sun
light & dietary intake
-Vt. D molecule lipophilic in nature →↑
Matrix factors effect → ↓ validity of the
assay.

19. J . A. Armed Forces Hospital
2006-2007 : Cobas 25(OH) vit.D assay
Most samples Low results
lowest levels : 0 ng/ml
Unstable readings for patients on tablets.
Good results ~ 100 ng/ml for patients on
injections.

20. New generation of the assay : total Vt.D
Total vitamin D results from randomly
selected 243 patients attending J.A. armed
forces hospital using method LIAISON,
diaSorin.
 We compared vt.D assay for samples at our
hospital (LIAISON, diaSorin:
chemiluminescent immunoassay technology)
and ROCHE, COBAS 6000 from Ministry of
Health hospital).

21. Both instruments are using chemileuscence
technology.
 We studied the link between total vt. D,
serum calcium, parathyroid hormone,
glucose and hba1c

22.  A 39 healthy volunteers to establish
laboratory reference range.
Patients' age 26-50 years old. Samples
withdrawn in foil covered plain tube. Results
analyzed using SPSS .
Results:
Vt.D
nmol/l
Calcium
mmol/l
PTH
pmol/l
glucose
mmol/l
Hba1c %
median 22.3 2.3 26.4 5.4 7.1
25 % I.Q.R 19.03 2.2 17.8 5 6.2
75% I.Q.R 58.1 2.4 60.8 6.5 9.1

23. Calculated volunteers reference range
(26.7- 90 nmol/l).
No relation was found between vt.D & ca
(P = 0.9), PTH (P = 0.4), Glucose (P = 0.6)
or hba1c (P = 0.2) Spearman’s correlation.
Conclusion
Measurement of total vt.D provides crude
assessment of its status but may give
inaccurate indication of its biological
activity.

24.  Satisfied?
 Major problem : tests over-usage?
 How to control ?

25. Most people have Vt.D levels < 75 nmol/l
as consequence of sedentary and largely
indoor life style.
Notes

26. Although it may be tempting to recommend
intentional sun exposure based on our
findings, it is difficult, if not impossible to
titrate one’s exposure. There are well-known
detrimental side effects of ultraviolet
irradiation. Therefore, oral supplementation
remains the safest way for increasing vitamin
D status.
( J Am Acad Dermatol 2010;62:929.e1-e9.)

27. Low vitamin D levels
 Dark Skin
 Obese
 Poor Dietary intake
 Malabsorbtion
 Poor Exposure to sunlight
 Drugs… Phynetoin, steroids

28. Clues:
Cancer risk reduced by vitamin D and
sunbathing.
Multiple sclerosis linked to long winters.
Sunshine vitamin prevents early diabetes.
Heart disease epidemic in sun-starved
Britons.

29. Vt.D dose
Adults over 50 years of age who are at moderate
risk for vitamin D deficiency. Supplementation
with at least 20–25 μg (800–1000 IU) of vitamin
D3 daily is recommended. To achieve optimal
vitamin D status (> 75 nmol/L), many individuals
may require supplementation at greater than 25
μg (1000 IU) daily

30. Treatment of severe deficiency (rickets or
osteomalacia) requires higher doses, e.g.,
1250 μg (50 000 IU) daily for two to four
weeks, then weekly or biweekly, with
monitoring of serum 25-hydroxyvitamin D at
one and three months.