Care is required interpreting 25OHD concentrations. If this patient was
taking a supplement that contains 25OHD2 rather than 25OHD3 the
immunoassays that are currently available to measure total 25OHD recognise
very little of the circulating form of 25OHD2. They also have different
reactivities and responses to 25OHD3. This is an important point when
reviewing the work published by Veith as he used an assay that does not
recognise vitamin D2 and has the strongest positive bias for D3 in DEQAS
and came out with the conclusion that vitamin D2 as a supplement was
relatively "inactive". The problems of assays are starting to be addressed
in some detail(see Glendenning et al Annals Clin Biochem 2003) and a
suggestion has been made that at present we should use assay specific
ranges when determining deficiency and toxicity.
Bill Fraser
--On 09 December 2003 10:55 +0000 Mohammad Al-Jubouri
<[log in to unmask]> wrote:
> I agree 25-OH vit D not terribly high to cause
> hypercalcaemia of 4.6 mmol/L on its own. She is
> obviously taking some vitamin D supplement of some
> sort, as serum 25-OH vit D level is higher than can be
> achieved by even the most enthusiastic sun bathers.
> Calcium and vitamin A supplements should also be
> sought meticulously in the history. Has she responded
> to high dose steroid or any other therapy?
>
> regards
>
> Mohammad
>
>
> --- ablumsohn <[log in to unmask]> wrote: > Not
> 100% convinced that this would be your sole
>> diagnosis. Enthusiastic lifeguards can get
>> plasma 25D in this sort of range, and they don't
>> generally get severe hypercalcaemia. There is an
>> argument proposed by some (eg Veith) that almost
>> everyone with 25D below the upper limit of the
>> summer
>> reference range you give (85nmol/L) is Vitamin D
>> deficient.
>>
>> It is pretty hard to make oneself severely vitamin D
>> toxic and markedly hypercalcaemic using easily
>> available sources of Vitamin D.
>>
>> Case reports of vitamin D intoxication with severe
>> hypercalcaemia generally have very high doses (eg
>> 50,000 units of Vitamin D per day for long periods
>> of time)
>> See for example N Eng J Med 345. 66 (2001), or the
>> Lancet case collection May 31st 1980 (mostly
>> iatrogenic).
>>
>> Possible, but.... what vitamin D did he take and
>> where
>> did he get it? Was it in the form of a calcium/D
>> supplement? - in which case he probably has calcium
>> rather than Vitamin D poisoning.
>>
>> Aubrey
>>
>>
>> DIB> I received the results of Vit D. The
>> DIB> patient was hospitalized the 25th
>> DIB> of November. The results of the specimen
>> DIB> taken the 1st of December
>> DIB> were:
>> DIB> 1,25 Vit D 118.2 pM (RV 41-145)
>> DIB> 25 Vit D 212.8 nM (RV summer 35 - 85;
>> winter 25 - 60)
>>
>> DIB> So most probably it was a case of vit D.
>> intoxication
>>
>> DIB> Thanks for your comments and suggestions in
>> this case.
>>
>> DIB> Ihssan
>>
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> =====
> Dr. M A Al-Jubouri
> Consultant Chemical Pathologist
>
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Professor W D Fraser
Department of Clinical Chemistry
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Tel: 0151 706 4247/4257
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