[Rich66]

On best test for D level (found in a LDN discussion):

There are two vitamin D tests--1,25(OH)D and 25(OH)D: 25(OH)D is the better marker of overall D status. It is this marker that is most strongly associated with overall health. The correct test is 25(OH)D, also called 25-hydroxyvitamin D.

According to the Vitamin D council:
Unfortunately, about 20% of United States doctors order the wrong test. They order a 1,25-dihydroxy-vitamin D, thinking that by measuring the most potent steroid in the human body, calcitriol, they are getting useful information. They are not. 1,25-dihydroxy-vitamin D is an adaptive hormone; it goes up and down with calcium intake. So these doctors see the 1,25-dihydroxy-vitamin D is normal or high and tell their patients that they are ok when really, they are vitamin D deficient""
http://www.vitamindcouncil.org/health/deficiency/am-i-vitamin-d-deficient.shtml

Here is a good article:
http://www.aacc.org/publications/cln/2009/july/Pages/CovStory1July09.aspx

The out-of-kilter 1,25 (OH)₂ D volume is no surprise to lab directors who are finding that not all physicians know which test —25-OH-D or 1,25 (OH)₂ D—is correct for determining overall vitamin D status. “ Fifty percent of physicians are still confused about what is the appropriate test. Some clients order both and one comes back normal and the other’s not. Then they call me and ask, ‘what should I believe?’ and I have to explain the difference,” observed L.V. Rao, PhD, director of core laboratories and associate professor of pathology at

Various:
The 25-OH Vitamin D test is the correct one.
Vitamin D, 25-Hydroxy
Synonyms:

• 25-Hydroxycalciferol
• 25-OH-D
• Cholecalciferol Metabolite
• Vitamin D
• Vitamin D₃ Metabolite
  

In the past year, ARUP Laboratories has experienced an increase in test volume for vitamin D testing. There has been some confusion regarding which test to order.
More at
http://www.labtestsonline.org/understanding/analytes/vitamin_d/test.html

Prostate cancer researchers say it's important that the type of vitamin D used in beneficial studies is Calcitriol. Most over the counter or prescription D are other forms.

Info on Rocaltrol brand of Calcitriol: http://rocaltrol.net/

Can't vouch for company, but generic Rocaltrol/Calcitriol available here:
http://trustedpharmacyworld.com/prod...item=Rocaltrol

from the PCa study:
"vCalcitriol (Rocaltrol 0.5 µg capsules, Roche Pharmaceuticals, Basel, Switzerland) 0.5 µg/kg was given orally in four divided doses over 4 hours on day 1 followed by docetaxel (Taxotere, Aventis Pharmaceuticals, Bridgewater, NJ) 36 mg/m² intravenously over 15 to 30 minutes on day 2 of each treatment week."



Home test available: http://www.zrtlab.com/vitamindcouncil/



Vitamin D toxicity issues discussed:
http://www.vitamindcouncil.org/vitaminDToxicity.shtml



CMSC-ACTRIMS: Content of OTC Vitamin D Low, Unpredictable


This report is part of a 12-month Clinical Context series.

By Richard Robinson, Contributing Writer, MedPage Today Published: June 07, 2010 Reviewed by Ari Green, MD; Assistant Professor, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner

Action Points Explain to interested patients that in one small but carefully done study, the actual dose of OTC vitamin D was below the listed dose in all brands tested. Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal. SAN ANTONIO -- Multiple sclerosis (MS) patients taking over-the-counter vitamin D aren't getting what they're paying for, or what their neurologists recommend, according to a study presented here. The mean vitamin D content from 10 OTC brands was only 33% of what the label claimed, with the actual content ranging from less than 1% to 82% of the advertised level. The study was presented at the meeting of the Joint Consortium of Multiple Sclerosis Centers and America's Committee on Treatment and Research in Multiple Sclerosis. Vitamin D supplements are increasingly being recommended to MS patients, both for osteoporosis, which is common in the disease, and for presumed immunomodulatory actions as well, according to senior author Peter Calabresi, MD, of the Department of Neurology at Johns Hopkins University in Baltimore. "As the role of vitamin D in immune regulation in MS gains increasing focus, oral supplementation is growing," he said. The level of recommended supplementation depends on the patient's individual deficiency, although 4000 IU daily is a common dose. However, given the wide variety of vitamin D3 (cholecalciferol) supplements available and "limited regulation within the nutritional supplement industry, the true vitamin D3 content of over-the-counter supplements is a concern," Calabresi said. To test levels in commonly purchased supplements, his group collected 10 bottles of OTC supplements from local and on-line retail pharmacies. Vitamin D3 was extracted by standard techniques and samples were analyzed by liquid chromatography and mass spectrometry. The labeled doses ranged from 400 IU to 10,000 IU, but the mean actual dose was only 33.5% of the labeled dose, with a range from 0.24% to 81.7%. Lower-dose products tended to be closer to their labeled dose than higher-dose products, with the three 400-IU products averaging 51.5%, the two 1000-IU products averaging 34%, and the three 10,000-IU products averaging 29.9%. On the other hand, the single worst sample -- the one with only 0.24% of what it claimed -- was a 400-IU sample. Neither national in-store retail brands nor online brands were more true to their labels. The discrepancy between the advertised and actual vitamin D content "may contribute to the difficulty for some patients to reach adequate serum vitamin D levels despite supplementation," Calabresi said. "This reflects the need for increased regulation of the vitamin industry." Because their lab is not certified to do drug testing, Calabresi declined to name the products tested in this study. Patients taking vitamin D supplements should have serum measurements made after starting therapy to determine whether they are reaching target levels, he said.

Primary source: Consortium of Multiple Sclerosis Centers Source reference: Eckstein C, et al "Vitamin D3 content in commercially available oral supplements" CMSC-ACTRIMS 2010; P. 33-34.

Arch Biochem Biophys. 2007 Apr 15;460(2):202-5. Epub 2007 Jan 8.
Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function.

Przybelski RJ, Binkley NC.
School of Medicine and Public Health, University of Wisconsin-Madison, 2870 University Avenue, Suite 100, Madison, WI 53705, USA. rjprzybe@facstaff.wisc.edu
Abstract

This study investigates the association of vitamin D status with cognitive function and discusses potential mechanisms for such an effect. The relationship of vitamin B12 with cognition was also assessed. A retrospective review of older adults presenting to a university-affiliated clinic providing consultative assessments for memory problems was performed. Charts of all patients (n=80) presenting for initial visits were reviewed to identify those who had serum 25-hydroxyvitamin D (25(OH)D), vitamin B12, and mini-mental state examination score (MMSE) all obtained on their first visit (n=32). Correlation analyses between MMSE and 25(OH)D and vitamin B12 levels were performed. Serum 25(OH)D concentration and MMSE showed a (p=0.006) positive correlation; no (p=0.875) correlation was observed between serum B12 concentration and MMSE. In conclusion, the positive, significant correlation between serum 25(OH)D concentration and MMSE in these patients suggests a potential role for vitamin D in cognitive function of older adults.

PMID: 17258168 [PubMed - indexed for MEDLINE]