I've done two 24 hour urine Calcium tests.
23rd of July 2012 Calcium 533 mg/24h (My Lab's ref value 100-350)
16th of Aug 2012 Calcium 225 mg/24h (My Lab's ref value 100-350) & Phosphat 619 mg/24h (My Lab's ref value 500-1300)
With the result of my 1st test my family doctor "reached for the prescription pad", he said it can be lowered with diuretic. He agreed to check it again first and added Phosphat as he said "they are connected".
After my 1st test I talked to my "Osteo coach" Dr Keith McCormick, he said:
"Check it again and this time really make sure you DO NOT take your calcium supplements the 24 hours before the start of the test or during the 24 hours of the test. So many times I see people high in this test simply because they took their calcium supplements the day before the test. Eat your regular diet including any dairy you normally eat though."
So by doing the test exactly like he said my 2nd turned out normal. And it isn't a borderline normal it is well within my Lab's ref value !
Not my family doctor nor my lab gave me any instructions before the test, only how to collect so I got 24 hours. So I knew nothing about restricting calcium supplements 24h before and during the test. I took my supplements (around 900mg Calcium) and ate my normal diet.
I wonder how many people get unnecessary diuretic prescriptions due to doing the test like I did the first time?
I have researched a little(!) what instructions are "out there".
But I have found many different instructions... !
1. "Drink the usual amount of liquids, eat your normal diet, and take the usual vitamins, calcium, and medications during the collection period."
2. "Do not take Calcium or Vitamin D supplements on the day of your collection and do not consume more than 400mg of dietary calcium on the day of collection"
3. "Ref value Adults: <300 mg/24 hours with low dietary calcium intake of 200 mg/24 hours" (I found that same instruction at the Medical University of South Carolina)
4. "Ref value Males: 25-300 mg/specimen* Females: 20-275 mg/specimen* Hypercalciuria: >350 mg/specimen *Values are for persons with average calcium intake (ie, 600-800 mg/day). Increased urinary excretion of calcium accompanies hyperparathyroidism, vitamin D intoxication, diseases that destroy bone (such as multiple myeloma), metastasis from prostatic cancer, and following calcium supplementation. Patients with absorptive hypercalciuria (increased gut absorption) will have lowered urine calcium with dietary restriction and, therefore, can be differentiated from patients with hypercalciuria caused by hyperparathyroidism, hyperthyroidism, Paget's disease, or "renal leak" type of calciuria as seen in renal tubular acidosis."
5. "a 24-hour urine specimen at least 2 weeks after stopping calcium supplements while continuing the usual dietary calcium intake" (page 25 of www.endojournals.org/site/translational/osteoporosis.pdf).
I will look for more instructions and interpretations of the 24 hour urine Calcium test but I wanted to post what I've found so far. Isn't this confusing?
Wouldn't it be nice if there where some sort of consensus?? What do you all think? Maybe this has been discussed before? /Lela