Osteoporosis at age 30 with high urine calcium, but no blood calcium nor high PTH

[ussrm]

I was diagnosed with Osteoporosis at age 30.
Blood tests showed no evelated blood calcium nor high PTH, all normal. They did show Vitamin D deficiency for which i'm taking 2000 iu daily.

However, 24 hour urine tests showed:
PHOSPHORUS- U 24h 1319 mg/24h
PHOSPHORUS- U SAMPLE 63 mg/dl
CALCIUM- URINE 24h 590 mg/24h
CALCIUM- U SAMPLE 28.1 mg/dl

Blood shows normal values, also for TSH and T4
1) TSH 1.95 mIU/L with normal range between 0.55 and 4.78 mIU/L
2) T4- FREE 14.1 pmol/L with normal range between 10 and 20 pmol/L

Though I have an endocrinology appointment in a month I would be happy to get some based answers (and not through Dr. google..)

thanks!