Gundberg CM, Looker AC, Nieman SD, Calvo MS Patterns of osteocalcin and bone specific alkaline phosphatase by age, gender, and race or ethnicity. Bone. 2002 Dec;31(6):703-8.
Horwitz MJ, Tedesco MB, Sereika SM, Hollis BW, Garcia-Ocaña A, Stewart AF Direct comparison of sustained infusion of human parathyroid hormone-related protein-(1-36) [hPTHrP-(1-36)] versus hPTH-(1-34) on serum calcium, plasma 1,25-dihydroxyvitamin D concentrations, and fractional calcium excretion in healthy human volunteers. J Clin Endocrinol Metab. 2003 Apr;88(4):1603-9.
Kalkwarf HJ, Specker BL, Ho M Effects of calcium supplementation on calcium homeostasis and bone turnover in lactating women. J Clin Endocrinol Metab. 1999 Feb;84(2):464-70.
Kovacs CS, Kronenberg HM Maternal-fetal calcium and bone metabolism during pregnancy, puerperium, and lactation. Endocr Rev. 1997 Dec;18(6):832-72. Review.
Kovacs CS Calcium and bone metabolism during pregnancy and lactation. J Mammary Gland Biol Neoplasia. 2005 Apr;10(2):105-18. Review.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
