Frequently Asked Questions

  1. Why is it important to study vitamin D?
  2. What are calcium isotopes?
  3. What do the 25-hour overnight visits involve?
  4. What are the physician function tests?
  5. What is a bone density scan?
  6. What is parathyroid hormone?
  7. What is a placebo?
  8. Is it dangerous to take vitamin D?
  9. Does my skin make vitamin D?
  10. Why do we collect a 4-day diet diary?
  11. What if I am interested in a study but do not qualify?
  12. What is the CRU?
  13. How do I find the hospital and clinics?
  14. How do I find the Osteoporosis Research Center?
  15. What is osteoporosis?
  16. What are optional studies that I see in the consent forms?
  17. Why do I have to fill out a W9 form for the IRS?


Q1: Why is it important to study vitamin D?
A1: Vitamin D is important for strong bone and healthy muscles. Vitamin D helps the intestines to absorb calcium from the food we eat. Our skin produces vitamin D in response to sunlight and we also obtain some vitamin D from food we eat. However, many people do not get enough vitamin D due to sun seeking and/or dietary habits.. Very low vitamin D levels can cause muscle weakness and an adult form of rickets. Researchers currently debate whether or not a mildly low vitamin D level causes any symptoms. In our research, we try to investigate whether or not correcting mildly low vitamin D levels improves bone health, muscle health and calcium absorption.

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Q2: What are calcium isotopes?
A2: Calcium isotopes are almost the same as 98% of the rest of calcium on earth (that you find in milk and other foods). The only difference is that the isotopes we use for research weighs slightly more than normal calcium. About 96% of calcium on earth has an anatomic weight of "40", Very small amounts of calcium with an atonimc weight of 42,43,44,46 an 48 exist. These calcium isotopes can be purchased and used to track calcium absorbtion. This difference in weight allows us to tell how much of the isotopes you absorb through your intestine. Stable isotopes are not radioactive and . are safe to use in children and pregnant women. Dr. Hansen tests all isotopes on herself before giving them to any study participant. In our studies, we give one calcium isotope through an IV in the arm. We mix another calcium isotope with orange juice to drink. During the next 24 hours, we collect all urine produced. From this urine, we measure how much of each isotope comes out with the urine and calculate the % calcium absorption.

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Q3: What do the 25-hour overnight visits involve?
A3: For your 25-hour visit, you will come to the UW Hospital research ward at 7:00 am after fasting from midnight the night before (nothing to eat or drink except water). To start, we will give you calcium isotopes by inserting an IV in your arm and by having you drink orange juice mixed with calcium (link to What are calcium isotopes?). We will collect some blood to measure your vitamin D and calcium levels. For 24-hours, we will collect all of the urine you produce. We will also give you all of your food and drink to consume. You cannot bring food or drink from home. We may ask you to complete some questionnaires and some physical function tests (link to what are the physical function tests). The rest of the time during those 24-hour is yours to relax. Although we ask that you stay on the ward, you are welcome to walk around the ward, bring movies, crafts, books, a laptop, etc for your enjoyment. The hospital does have public wireless internet to use. Prior participants have felt that the 24-hour visits are a nice break from daily life.

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Q4: What are the physician function tests?
A4: In our studies, we perform two physical function tests. One is called a sit-to-stand test. In this test, we will ask you to sit in a chair and then stand up and sit back down five times in a row. We will time how long it takes you to complete this test. The second test is called the timed-up-and-go test. In this test, we will ask you to sit in a chair, stand and walk to a line on the floor then walk back and sit back down. Again, we will time how long this task takes for you to complete.

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Q5: What is a bone density scan?
A5: A bone density scan is an X-Ray to measure your bone calcium levels. It is a painless test that takes about 15 minutes to complete. During the scan, we will ask you to lie flat on a table while the machine scans over you. The radiation dose from the bone density test is about 15% of the radiation dose from a chest x-ray.

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Q6: What is parathyroid hormone?
A6: Although it sounds similar, parathyroid hormone is different than thyroid hormone. The four parathyroid glands are located near your thyroid gland in your neck. When blood calcium is too low, these glands release parathyroid hormone to help bring the blood calcium back up to normal. Parathyroid hormone does this in two ways. First, it tells your bone to release calcium into your blood stream. Second, it helps activate vitamin D so that vitamin D can make your intestines to absorb more calcium. Because parathyroid hormone is important for calcium, we measure it in our studies.

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Q7: What is a placebo?
A7: A placebo is a sugar pill. In some of our studies, we use a placebo as a control arm. This will allow us to compare how calcium absorption or bone density changes in women who take vitamin D versus women who do not take vitamin D. The placebo looks the same as the vitamin D. This is to keep us from finding out who is taking vitamin D versus who is taking placebo. If we knew who took which treatment, we could interpret our study results incorrectly.

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Q8: Is it dangerous to take vitamin D?
A8: For the most part, vitamin D is safe for people to take. However, really high doses of vitamin D can cause a high blood calcium, a high urine calcium or kidney stones. Although we give participants high-dose vitamin D, the doses we use in this study have not caused any of these side effects. Furthermore, these high doses do not cause side effects in other researchers' vitamin D studies. However, to be sure it is safe for you to participate in the study, we measure blood calcium and urine calcium throughout the course of your participation.

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Q9: Does my skin produce vitamin D?
A9: Yes! Your skin does produce vitamin D in response to sunlight (UVA and UVB rays). However, naturally pigmented skin can limit how much vitamin D we produce. Sunscreen can also block production of vitamin D. In addition, people who live in more northern climates do not receive as much sun exposure as people who live nearer to the equator. Without adequate sun exposure, we may not produce enough vitamin D for good bone health.

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Q10: Why do we collect a 4-day diet diary?
A10: 4-day diet diaries help us to know what types and how much food you typically feed yourself. During your 25-hour visits, we give you all of your food and drink to consume. We try our hardest to match the food that you typically feed yourself. These diet diaries also help our research as diet can influence vitamin D and calcium absorption. We do not judge the types of foods you eat; we just want to collect enough information to feed you correctly at your hospital stay.

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Q11: What if I am interested in a study but do not qualify?
A11: We may have another study for you to participate in or another study planned for the future. If you like, we can call you at a future time for participation in a new study. In addition, the Osteoporosis Clinical Research Center has a registry of participants to contact for future research. To sign up for this registry, click here: (link to registry).

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Q12: What is the CRU?
A12: The CRU stand for the Clinical Research Unit. Basically, this is the ward of the hospital where research subjects complete study visits. The nurses who work in the ward are highly trained research nurses and are friendly and helpful for our research studies.

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Q13: How do I find the hospital and clinics?
A13: For a map and directions to the hospital and other clinics we use for our studies, click here.

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Q14: How do I find the Osteoporosis Research Center for my bone density appointments?
A14: For a map and directions to the Osteoporosis Research Center we use for our studies, click here.

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Q15: What is osteoporosis?
A15: Osteoporosis is a condition where your bone density is lower than it should be. This decrease in bone density makes our bones more fragile and could put us at a higher risk for fracture or spine curvature. We measure bone density with a bone density scan (link to what is a bone density scan). If we measure your bone density and find osteoporosis, we will give you some advice on how to talk to your doctor about treatment. We do not allow women with osteoporosis to participate in our research studies.

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Q16: What are optional studies that I see in the consent forms?
A16: These optional studies are asking whether or not you allow us to save blood, urine or a DNA sample for possible future use. At this time, we do not have a specific plan for these samples. However, we may find a new test or a new gene in the future. If we do find a new test or gene, we could use our bank of samples to conduct a new research study. These samples are kept in a locked laboratory and are only labeled with a unique study ID code, not any personal identifying information. The only people who have access to these samples are Dr. Hansen and her research team. You can agree or disagree to participate in these studies. Your decision is voluntary and will not affect your participation in the study as a whole.

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Q17: Why do I have to fill out a W9 form for the IRS?
A17: Anytime the UW pays subjects more than $600 in a calendar year, we have to report this as income to the IRS. Unfortunately, we cannot get around this or adjust study payments to avoid this.

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