RecommendeddailyvitaminDintakesareofteninsufficienttocorrectsecondaryhyperparathyroidisminpatientswithprimaryosteoporosisandosteopenia,Canadianresearchersreport.
“TheOsteoporosisSocietyofCanadarecommendsthatpatientswithosteoporosistake800IUvitaminDdaily,”sayEdmundYendtandcolleaguesfromQueensUniversityinKingston,Ontario.
“Atbaseline,vitaminDintakesexceeded800IUdailyin19%ofourpatientswithsecondaryhyperparathyroidism,sothisdoseisclearlyinadequateforsomepatients,”theyadd.
Yendtandteammeasuredbiochemicalvariables,renalfunctionandcalciumandvitaminDintakesin218femalepatientswithprimaryosteoporosisorosteopenia.
Atbaseline,75patientshadparathyroidhormone（PTH）levelsintheuppersixthofthereferencerange,indicatinghyperparathyroidism.Theremaining143patientshadPTHlevelsintherestofthereferencerange.
Patientsweretreatedwitheither1000IUofvitaminD3dailyor50000IUofvitaminD2onceweeklyandfollowed-upafter1year.Inaddition,theresearchersfollowed-uppatientswithsecondaryhyperparathyroidismuntilPTHlevelsbecamenormal.
Inone-thirdofthehyperparathyroidpatients,thestandardbaselinetreatmentfailedtocorrectthesecondaryhyperparathyroidism,theresearchersreportinthejournalClinicalEndocrinology.
Specifically,unusuallyhighdosesofvitaminD（50000IUvitaminD2twiceweekly）wererequiredtorestoreserumPTHlevelstonormalinninepatientswithnoevidenceofceliacdiseaseorothermalabsorptivedisorders.
TherewerealsosixpatientswhoseserumPTHlevelsonlyreturnedtonormalwhensupplementalcalciumintheformofcalciumcarbonatewaschangedtocalciumcitrate.
Yendtetalconclude:“LargedosesofvitaminDarefrequentlynecessarytosuppresssecondaryhyperparathyroidisminpatientswithprimaryosteoporosisandosteopenia.ThissuggeststhatvitaminDmetabolismmaybealteredinsomeofthesepatients.”
