Assessment of intestinal calcium absorption and calcium kinetics for bone resorption and bone formation rates using dual stable isotopes

Study ID
STU 102010-130

Cancer Related
No

Healthy Volunteers
Yes

Study Sites

Contact
Ashlei Johnson-Wilder
214-648-0394
ashlei.johnson@utsouthwestern.edu

Principal Investigator
Khashayar Sakhaee

Summary

all subjects will undergo screening to determine eligibility. This will include a blood draw and/or 24-hour urine collection.

aiM 1: on Day 0, subjects will be admitted to the CTRC. They will be given a metabolic dinner. They will fast from 6PM on. on Day 1, subjects will collect a 2-hour fasting urine, after which they will begin a 24-hour urine collection. They will drink a mixture of non-isotopic calcium and stable calcium isotope mixed in ensure. Simultaneously, a stable calcium isotope will be infused intravenously. Breakfast will be withheld, but a metabolic lunch and dinner will be served. a blood sample will be collected. Blood sampling will continue hourly for 8 hours and every 2 hrs afterward. on day 2, a fasting blood sample will be collected and the subject discharged from the CTRC.

aiM 2 and 3: on Day 0, subjects will be admitted to the CTRC. They will be given a standard metabolic dinner. They will fast from 6PM on. on Day 1, subjects will collect a 2-hour fasting urine, after which they will begin a 24-hour urine collection. They will drink a mixture of non-isotopic calcium and stable calcium isotope mixed in ensure. Simultaneously, a stable calcium isotope will be infused intravenously. Breakfast will be withheld, but a metabolic lunch and dinner will be served. a blood sample will be collected and a second blood sample will be collected at the time determined based on aim 1. on day 2, the subject will be discharged from CTRC.

aiM 4: on days 0-1, Patients will eat a low salt/low calcium diet for 2 days. Dietary records will be kept. on days 2-3, subjects will receive a frozen metabolic diet. They will be admitted to the CTRC on day 3. a standard metabolic dinner will be provided. They will fast from 6PM on. on day 4 subjects will collect a 2-hour fasting urine, begin a 24-hour urine collection, and a fasting blood sample will be drawn. Subjects will drink a mixture of stable calcium isotope and ensure. Simultaneously, a stable calcium isotope will be infused intravenously. Blood will be collected at specific time points over 8 hours. Breakfast will be withheld, but a metabolic lunch and dinner will be served. The patient will complete their 24-h urine collection on day 5, after which they will be given a metabolic breakfast and 300cc distilled water. They will be discharged from the CTRC the morning of day 5 following a spot urine at 10:00am. another spot urine will be collected at 8:00pm. Two spot urines will be collected at 8:00am/8:00pm on days 6-10. Spot urine specimens will be returned to the CTRC on days 8 and 11.

Participant Eligibility

Aim 1: 6 healthy adult patients (20-50 years of age) of either gender.

Aim 2: 2 healthy adult subjects (>20 years of age < 40 years, premenopausal) of either gender, 2 elderly subjects (> 60 years and < 80 years) of either gender with urinary calcium of less than 150 mg in 24 hours, and 2 subjects (>20 years of age < 80 years) of either gender with primary hyperparathyroidism.

Aim 3: 4 subjects (>20 years of age < 80 years) with reduced GFR (15-30 cc/min). Vitamin D supplements, calcium supplements and calcium based phosphate binders will be held 4 week prior to the study

Aim 4: 10 hypercalciuric stone forming subjects and 10 normocalciuric stone forming subjects. 21-50 years of age, any ethnicity, and either gender.