Circulating Vitamin D Levels

Beth Zubal, MS, AOCNP, FNP-BC

D History…• 1822 – Sniadecki: Clinical observation of urban children

with ↑rickets compared to rural children

• By 1900, 80% of Boston children had rickets (pollution)

• 1930s, food fortified with Vitamin D,Schlitz Brewery (Milwaukee, WI) introduced beer fortified with Vitamin D

• 1980, Coppertone developed UVA/UVB sunscreen

Holick MF. VITAMIN D AND HEALTH IN THE 21ST CENTURY: BONE AND BEYOND. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Amer J Clin Nutr, Vol. 80, No. 6, 1678S-1688S, December 2004.

Sniadecki J. Jerdrzej Sniadecki (1768–1838) on the cure of rickets (1840); cited in Mozolowski W. Nature 1939;143:121–4.

20,000 IU of Vitamin D < 30 min of sunlight

=200 glasses of milk or 50 standard multivitamins (400IU/tab) in one sitting

Cannell, JJ, Hollis BW, Zasloff M et al. Diagnosis and treatment of Vitamin D deficiency. Expert Opin Pharmacother (2008) 9(1), 107-118.

Selected Food Sources of Vitamin D

FoodIUs per serving*

Percent DV**

Cod liver oil, 1 tablespoon 1,360 340

Salmon, cooked, 3.5 ounces 360 90

Mackerel, cooked, 3.5 ounces 345 90

Tuna fish, canned in oil, 3 ounces 200 50

Sardines, canned in oil, drained, 1.75 ounces 250 70

Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup 98 25

Margarine, fortified, 1 tablespoon 60 15

Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV)

40 10

Egg, 1 whole (vitamin D is found in yolk) 20 6

Liver, beef, cooked, 3.5 ounces 15 4

Cheese, Swiss, 1 ounce 12 4

*IUs = International Units**DV = Daily ValueTable from Office of Dietary Supplements: NIH. Retrieved January 15, 2009 http://ods.od.nih.gov/factsheets/vitamind.asp

Circulation

Vitamin D enters circulation through

• Skin (D to D3) (Endogenous)

• Diet (D3) (Exogenous)

• Supplements Vit D2 - ergocalciferol

D3 - cholecalciferol

• Prescription – Calcitriol (synthetic analog)

D Conversion:

• Liver converts to inactive 25 (OH)D (=calcitriol) by cytochrome P450

• Kidney = “gets it going” 25(OH)D physiologically active to 1,25(OH)D most potent form of Vit D

• Parathyroid – stimulates synthesis

1,25(OH)D maintains calcium level

Intestine↑ absorption dietary Ca++

Kidney(active D=calcitriol)

Parathyroid

Liver (inactive D)

Parathyroid Hormone

• During hypocalcemia, responsible for:

– Mobilizing bone calcium

– Increasing reabsorption of calcium by kidneys

– Intestinal absorption of calcium

Definitions

• Normal level of 25-Hydroxy Vitamin D:– > 30 ng/ml

• Insufficiency:– 21 – 29 ng/ml

• Deficiency:– < 20 ng/ml

From: Holick (2008) Nutrition Reviews, Vol 66 (Suppl 2), S182-S194

Levels Associated with Disorders

• Prevention of rickets and osteomalacia– 15 ng/ml

• Supression of parathyroid hormone– 20 – 30 ng/ml

• Optimal intestinal absorption of calcium– 34 ng/ml

• Neuromuscular function/performance– 38 ng/ml

Cannell, Hollis, Zasloff, & Heaney. (2008). Expert Opin. Pharmacother. 9(1): 107-118.

Serum 25-Hydroxyvitamin D [25(OH)D] Concentrations and Health

ng/mL**nmol/L**

Health status

<11 <27.5 Associated with vitamin D deficiency and rickets in infants and young children

<10-15 <25-37.5

Generally considered inadequate for bone and overall health in healthy individuals

≥30 ≥75 Proposed by some as desirable for overall health and disease prevention, although a recent government-sponsored expert panel concluded that insufficient data are available to support these higher levels

Consistently >200

Consistently >500

Considered potentially toxic, leading to hypercalcemia and hyperphosphatemia, although human data are limited. In an animal model, concentrations ≤400 ng/mL (≤1,000 nmol/L) demonstrated no toxicity

* Serum concentrations of 25(OH)D are reported in both nanograms per milliliter (ng/mL) and nanomoles per liter (nmol/L).** 1 ng/mL = 2.5 nmol/L.Table from Office of Dietary Supplements: NIH. Retrieved January 15, 2009 http://ods.od.nih.gov/factsheets/vitamind.asp

Dosing Recommendations for Deficiency

• Insufficiency– 800 – 1,000 IU of D³ daily– Brings level to 30ng/ml in 3 months

• Deficiency– Initial dose: 50,000 IU of D² or D³ po weekly for 6 – 8 weeks – Subsequent dose: 800 – 1,000 IU of D³ daily

• Malabsorptive States– Doses from 10,000 – 50,000 IU daily may be needed

Covered Diagnoses

• Hypocalcemia

• Persistent, nonspecific musculoskeletal pain

• Fatigue

• Those on anticonvulsant therapy

• Suspected toxicity

Factors Contributing to Decreased Levels

• Living in a northern latitude- > 35º• Melanin content in skin• Age: Elderly • Obesity• Use of sunscreen• Clothing coverage• Breast fed infants

Vitamin D Deficiency in the Elderly

Symptoms Associated with Vitamin D Deficiency

• Muscle weakness• Myalgia• Bone pain• Nausea• Hypocalcemia• Hyperparathyroidism• Osteopenia• Fractures

Frequency of Testing

• At risk patients– Check twice a year, once in early spring to

determine lowest level and again in late summer for peak level.

• Those started on treatment– Three months after therapy initiated

Drug Interactions with Vitamin D

• Steroids• Anti-convulsants: phenytion• Bile acid sequestrants: Questran• Thiazide diuretics given to patients with

hypoparathyroid on D2 may cause hypercalcemia

• Mineral oil effects absorption

Laboratory Tests for Vitamin D

• 25-Hydroxy Vitamin D

• 1,25-Dihydroxy Vitamin D

• Vitamin D panel: includes 25-Hydroxy and 1,25-Dihyroxy levels

Functions of Vitamin D

• Promotes calcium absorption from gut• Maintain adequate calcium and phosphate

concentrations• Modulates neuromuscular and immune

function• Reduces inflammation• Has a role in cell proliferation, differentiation,

and apoptosis

Consequences of Vitamin D Deficiency

• Skeletal– Osteoporosis– Osteomalacia and bone pain– Muscle weakness

• Nonskeletal– Chronic disease: autoimmune diseases,

osteoarthritis, diabetes– Cancer– Tuberculosis– Cardiovascular disease

Holick, M. N Engl J Med, 2007;357:266-281; Wicherts et al. J Clin Endocrinol Metb. 2007;92:2058-2065. ; van Loden et al. Semin Oncol. 2008;35(6):643-651.

PharmacogenomicsNearly 200 human genes contain vitamin D

receptors (1)

(brain, pancreas, heart, GI tract, immune system, prostate, bones)

Binding of VDR by calcitriol leads to multiple cellular effects: apoptosis, angiogenesis and potential of metastasis (2)

1. Carlberg C. Current understanding of the function of the nuclear vitamin D receptor In response to its natural and synthetic ligands. Recent Results Cancer Res. 2003; 164: 29-42.

2. Ng K, Meyerhardt, JA, Wu K, et. al. Higher pre-diagnosis plasma levels of serum 25-hydroxy-vitamin D (25[OH]D) after a diagnosis of colorectal cancer may significantly improve overall survival. J Clin Oncol 26(18), 2984-2991, 2008.

Fok1 polymorphism

• Vitamin D receptor (VDR) important role in Vitamin D pathway• May be greater in European women

• Steroid family of nuclear receptors

• More than 80% of breast cancers are VDR +

Tang C, Chen N, Wu M, et al. Fok1 polymorphism of vitamin D receptor gene contributes to breast cancer susceptibility. Breast Cancer Res Treat. Published online: 06 January 2009: DOI 10.1007/s10549-008-0262-4.

Breast Cancer

94% more likely to develop metastases and 73% more likely to die than women with normal levels of vitamin D at diagnosis

Goodwin P. Frequency of vitamin D (Vit D) deficiency at breast cancer (BC) diagnosis and association with risk of distant recurrence and death in a prospective cohort study of T1-3, N0-1, M0 BC. American Society of Clinical Oncology Annual Meeting: Abstract 511. 2008.

Balance of Calcium

Vitamin D balance is crucial for proper calcium utilization including:

calcium absorptionbone growthosteoclast/osteoblast activity

Bone Loss and Breast Cancer

• Treatment with Aromatase Inhibitors (AIs)

• Chemotherapy causing ovarian failure

• Radiotherapy

Hadji P, Body JJ, Aapro MS, et al. Practical guidance for the management of aromatase inhibitor-associated bone loss. Ann Onc 2008 Aug; 19(8): 1407-16. Epub 2008 Apr 29.

Vitamin D deficiency-incidence and response to oral supplementation

among various gastrointestinal malignancies

Gilmore C, James J, Zubal B, Thomas D, Tan B

Washington University School of Medicine

Siteman Cancer Center

St. Louis, MO

Gilmore C, James J, Zubal B et al. Vitamin D deficiency-incidence and response to oral supplementation among various gastrointestinal malignancies. 2009 GI ASCO. Abstract No: 329.

Gilmore C, James J, Zubal B et al. Vitamin D deficiency-incidence and response to oral supplementation among various gastrointestinal malignancies. 2009 GI ASCO. Abstract No: 329.

Gilmore C, James J, Zubal B et al. Vitamin D deficiency-incidence and response to oral supplementation among various gastrointestinal malignancies. 2009 GI ASCO. Abstract No: 329.

Treatment

Pts with 25-OH Vitamin D level < 20-Vitamin D 50,000u q week x12

Pts with 25-OH Vitamin D level 21-50-Vitamin D 50,000u q week x8

Serum 25-OH re-checked after 8-12 weeks of therapy and if still <50 ng/ml continued on therapy according to above guideline

Goal to get 25-OH vitamin D level to 50 ng/ml and then maintain with 1000 to 2000u q day

Gilmore C, James J, Zubal B et al. Vitamin D deficiency-incidence and response to oral supplementation among various gastrointestinal malignancies. 2009 GI ASCO. Abstract No: 329.

Gilmore C, James J, Zubal B et al. Vitamin D deficiency-incidence and response to oral supplementation among various gastrointestinal malignancies. 2009 GI ASCO. Abstract No: 329.

Gilmore C, James J, Zubal B et al. Vitamin D deficiency-incidence and response to oral supplementation among various gastrointestinal malignancies. 2009 GI ASCO. Abstract No: 329.

Gilmore C, James J, Zubal B et al. Vitamin D deficiency-incidence and response to oral supplementation among various gastrointestinal malignancies. 2009 GI ASCO. Abstract No: 329.

Conclusions

• Vitamin D Deficiency is common among patients with GI malignancies.

• Vitamin D levels should routinely be evaluated for patients with GI malignancies.

• Oral supplementation decreases the rate of ‘any’ vitamin D deficiency from 81% to 61%, and of ‘severe to moderate’ deficiency from 58% to 17%.

• Prospective studies on the impact of vitamin D deficiency and supplementation on various clinical outcomes among patients with GI cancers would improve supportive care management of these patients.

Who should undergo serum testing?

or

Should we be asking,

Who should not?

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