Testing Bone Density Variables and the Results

Alicia Hull

East Tennessee State University

Abstract

            This study is researching the facts about food and bone metabolism. The affects of vitamins and minerals have been tested and have proved that these supplements do affect the bone density results on a densitometry scan. However, there are underlying factors, such as food, that may also change the results of the bone density scan. The purpose of this study is to further the knowledge of how the bone metabolizes nutrients, and to gain more information on bone density disorders. Since there are so many bone density abnormalities, the study would only be using a few select disorders to test the food variables. Hopefully the results of this study will inform not only the physicians, but also the patients about the affects food may or may not cause on bone density. The main questions guiding this research are:

·      Could eating before a bone density scan affect the results?

·      How does food affect bone density?

·      Do certain foods affect bone density differently?

Acknowledgements

This research study may not appear too fancy, but the results could change the results of how patients with bone density disorders are diagnosed. Though I have learned plenty through researching for this study, there is still more information on these subjects that I have not learned about. In this paper I would like to acknowledge my family and friends who have helped and pushed me through this project. Without their support, I do not know how I would have done this research project. Now that the semester is almost over, I am glad to say I’ll be free of stressful classes until next fall!

Chapter I Introduction

BACKGROUND

Bone Density

Bone density tests are usually performed on women ages 60-65, to measure the mineral and calcium percentage of their bones. If bones lack calcium they are more likely to fracture. Bone density tests also test to indicate the extent of osteoporosis. Osteoporosis is a disease that affects the bone density and causes the bones to become more likely to break. In an article about bone density tests. “Today, a bone density test, also called a densitometry or DEXA scan, can determine if you have osteoporosis or are at risk for osteoporosis before you break any bones” (Mayo Clinic, 2008, p. 1). Patients at risk for osteoporosis are not just middle age women, but also include those with eating disorders can also suffer from osteoporosis.

There are many different types of machines that measure bone density on the patient. A dual energy x-ray absorptiometry (DEXA) method is used on patients mainly when testing the spine, hip, or entire body. The DEXA method is the most commonly used technique. A peripheral energy x-ray absorptiometry (PDXA) tests the peripheral bone density on a skeleton. Specifically, this tests the heel, wrist, or finger for the bone content. A single energy x-ray absorptiometry (SXA) is usually used to test the bone density in the patient’s wrist and heel. The single photon absorptiometry (SPA) is used only when testing the bone content in the wrist. The dual photon absorptiometry (DPA), like the DEXA method, measures the bone density of the hip, spine, or the whole body. However, the SPA and DPA are not used very frequently. A quantitative computed tomography (QCT) can be used to measure the bone density of the entire body, or just the spine. Unfortunately, when using the QCT the patient is exposed to a significantly higher amount of radiation than normal. Normal radiation on a patient is about 0.005 of an entire radiation wave. Usually the QCT method is not used repeatedly on the same patient nor is it used on the patients of childbearing age. The radiographic absorptiometry (RA) method is used specifically when measuring the bone density of the entire hand. A RA uses a special x-ray technique in order to calculate the bone density (Optum Health, 2008).

PURPOSE

Study of Bone Density Tests

The purpose of this study is to determine if eating before a bone density test could affect the test’s results? For example, patients who have taken calcium pills before a densitometry exam, the results can change. Most physicians ask the patient to stop taking any calcium supplements 24 hours before the day of the patient’s densitometry exam. Also, having an exam that involves ingesting barium, such as a CT Scan prior to a bone density test can affect the results of a bone density test. Patients undergoing procedures using barium may have to wait 10-14 days before a bone density exam. When a person eats, part of the fat, calcium, and other minerals are absorbed into the bones. Considering calcium pills affect the results of a densitometry exam, why would eating not affect the outcome of the test? Franklin Memorial Hospital requires that patients, “Please do not take any calcium pills (including TUMS) or multivitamins for 24 hours leading up to the time of the exam. We will not be able to do your exam if you have taken these pills”; however the website also reads, “You can eat normally before the exam- it will not interfere with the results” (Franklin Memorial Hospital, n.d., p.1). These statements tend to contradict each other.

SIGNIFICANCE

Affects of Food

If eating before a bone density test does affect the results, then physicians, technicians, and the patients need to be aware of this. Since there are other factors, such as multivitamins, could affect the results, it makes sense that food would also. Finding out about the affects of ingesting food before one of these exams, would give the patients and doctors a timeline of when the patient could and could not eat before an exam. The results of this research could change how patients prepare for a densitometry exam. This would include not eating for a certain time period before a densitometry exam, or only eating certain foods before.

RESEARCH QUESTION

Affects on Bone Density Test

A single question guided this research: Would food affect the results of a bone density test? The research question in simpler terms is would foods ingested in a normal diet affect the results. If the results indicate that such foods do, a logical follow-up question would be, what type of foods could affect the results of a bone density test? Testing the impact of different types of foods on densitometry results, (for example, foods with a high fat content, foods enriched with vitamins, foods containing calcium, or foods that are considered healthy) is important to the study. Healthy foods would be fruits and vegetables. Another question that could guide this research: Why does food not affect the results of a bone density test? The researcher needs to take into consideration the patient’s diet, for example, if the patient is at a healthy weight, or if the patient is overweight.

ASSUMPTIONS

Machines and Methods

This study makes the following assumptions:

1.     Densitometry machines used to collect data are working properly.

2.     The correct densitometry method is used.

LIMITATIONS

Patients

This study is limited to patients in Tennessee and studies performed during the months of August through December of 2008. Having a good selection of patients to participate in the study is important since every patient is different. Considering not all of the patients who are going to get a bone density scan have osteoporosis, each patient will most likely be tested in different parts of the body. For example, every patient will not have his or her heel’s bone density tested. This also means, that there will be different methods used on the patients. As discussed earlier, there are different methods used on patients depending on where the technicians are examining the bone density.  It could be important that all of the patients used in the study are around the same weight; since, weight could be a factor in affecting the results of a bone density test.

Chapter II Literature Review

LITERATURE

Bone Density

Bones are the structure of the human body, without correct formation or growth, abnormalities or disorders can occur. Jowsey (1977) detailed, “Disease implies pain and discomfort. In metabolic bone disorders, it implies that a fracture of deformity of the bone has occurred to cause the subsequent pain and discomfort” (p.161). Bone density scans are one of the many tools to detect an abnormality. Whalen (1978) wrote, “Before abnormality of a structure can be appreciated, an understanding of the mechanism by which bone grows is required” (p.1). Examples of bone abnormalities or diseases would be osteoporosis, osteopetosis, and osteogenesis imperfecta (Whalen 1978, p. 31). Forming, modeling, remodeling, absorb, are all common terms when diagnosing a bone disorder. Simon and Krane (1983) explained these steps as:

“Bone is a dynamic organ continually remodeled during life through complex process of organized cellular activity. Remodeling is initiated by osteoclasts which resorb old bone and is followed by deposition of new bone by osteoblasts. Resorption and formation are tightly coupled in the normal state so that the mass old the bone does not change. (p.108)

Jowsey (1977) wrote, “…most metabolic bone disease is diagnosed as a result of the fracture, frequently many years after the bone disorder has been in existence and causing bone loss” (p.162). Some bone disorders can be treated with special diets. Most physicians require a patient who is receiving a bone scan to stop taking minerals or vitamins 24 hours before the exam (RadiologyInfo, n.d.), because these could change the density of bones. Therefore, food should affect the results of a bone density scan as well.

DISORDERS

Bone Abnormalities

Whalen (1978) described one of the bone abnormalities as, “Osteopetrosis is a disease of universal failure of modeling” (p.31). This bone abnormality can be detected through bone scans. Depending on where the bone issue is depends on the type of scan used to read the bones. Bone density scans measure bone loss (RadiologyInfo, n.d.). Another reason for bone loss is called age related. Age related bone loss is not a disease, but it is still considered an abnormality. As people get older, the bones in the human body deteriorate. Abnormalities are detected with an x-ray machine with different levels of ionizing radiation.

            A common abnormality in bone density is osteoporosis (Johnston, 1983, p.317) and Mohan (1983) agreed with this statement, “Osteoporosis, which affects one fourth of North American postmenopausal women, is characterized by accelerated net loss of bone mass which results in increased susceptibility to fractures” (p.173). Siegelman (1987) provided further information on osteoporosis with, “Osteoporosis is a common skeletal condition characterized dynamically by a significant period in which bone resorption exceeds bone production; physically by a reduction of calcified bone mass per unit volume of bone…” (p.153). Gallagher (1983) tested, “Two major studies have reported that a large proportion of patients with osteoporosis have impaired calcium absorption. In about one third of patients the absorption problem is so marked that the fecal calcium exceeds the calcium intake” (p.364). There are different levels of osteoporosis, such as, osteoporosis, juvenile osteoporosis, post-menopausal osteoporosis, and severe osteoporosis. Each level of osteoporosis has different effects on the body. When Siegleman (1978) wrote, “Severe osteoporosis produces compression deformities of the spine, but there is a phase of the disorder characterized by alterations without deformity (p.154-155), he meant that there are cases of osteoporosis when the patient’s spine does not curve. In concerning the mineral content due to osteoporosis, Reeve (1983) study read, “We have recently shown that in osteoporosis, calculated rates of whole body bone formation correlated significantly with calcium balance data when corrected for ‘long-term’ exchange but not when calculated without this correlation” (p.100). The correlation that Reeve mentioned was about the tetracycline labeled osteoid surfaces and unlabeled osteoid. Mohan (1983) also referred to another correlation:

We have proposed that the failure of bone formation to balance bone resorption in osteoporosis {thus resulting in net bone loss} may be due to a progressive defect in coupling – a regulatory mechanism by which bone formation is stimulated in proportion to bone resorption (p.173).

BONE DENSITY

Test Methods

            Measuring bone density is done with a few different methods, depending on where in the body the physicians are testing. Examples of different methods are single energy x-ray transmission method, dual energy transmission method (DEXA), computed tomography (CT or QCT), and scattered photon techniques (Joseph, 1978, p.177-179).  Joseph (1978) applied his knowledge about bone density testing with, “It has become apparent that a method for accurately measuring the mineral content of bodes in vivo is of crucial importance for diagnosing and managing many types of metabolic bone diseases” (p.175).  Compared between QCT and DEXA, “The potential advantage of QCT over dual photon absorptiometry is its capability for precise 3-dimensional anatomic localization and for spatial separation of highly responsive cancellous bone from less responsive cortical bone” (Genant, 1983, p.40) described only one of the differences among all of the bone density scans. The DEXA method is non invasive and explained by a, “Measurement of bone mineral of the lumbar spine by dual photon absorptiometry is a routine clinical test as well as a research tool” (Wahner, 1983, p.34). Along with the different measuring methods, only certain methods can measure specific bones. 

VITAMINS

Breakdown of Bone

Minerals, vitamins, and hormones are needed in the bones, such as calcium, calcitonin, cortisol, and vitamin D. Bones absorb and reabsorb minerals and vitamins that come from the plasma. With skeletal homeostasis, Rasmussen (1983) suggested, “For example, it is clear that the process of bone mineralization can take place normally when the plasma calcium concentration is as low as 5 mg/dL or as high as 15 mg/dL” (p.83). Vitamin D was mentioned as, “Traditional views of the action of vitamin D are that this agent has two major physiological effects: it increases mineral ion absorption in the intestine, and it increases the resorption of mineral ions from bone” (Rasmussen, 1983, p.85). Since vitamin D plays such a large role in resorption, it is also explained, “… vitamin D increases bone growth, bone mass, and mineralization by some direct effect on the formation-mineralization side of bone modeling and bone remodeling” (Rasmussen, 1983, p.85). Calcium affects the growth with structural metabolic, and Lanyon (1983) suggests, “’Metabolic remodeling’ is required to provide a supply of mineral to maintain serum Ca” (p.183). An additional factor in bone remodeling is, “Hormones are known to influence the number of remodeling sites, and perhaps the rate of remodeling as well… The major stimulators of resorption are parathyroid hormone and…vitamin D3, and the major inhibitor is calcitonin, although cortisol may act as a resorption inhibitor at physiological concentrations” (Peck, 1983, p.179).

The formation of bones has many detailed steps, Krane (1983) described one of the steps, “In the process of bone formation, mineral ions enter the inorganic phase; these ions are then removed in the process of bone resorption” (p.96). Bones have many stages to go through, and, “Remodeling has received considerable attention because it becomes abnormal in most metabolic bone disorders. Efforts have been directed towards measuring rates of new bone formation and resorption, both locally in the skeleton as a whole” (Reeve, 1983, p.99).  Having bones formed with the correct sequence is necessary, and Peck (1983) writes it best as, “Of particular importance in the remodeling scenario are the factors that might link resorption and formation” (p.180). Another fact about bone remodeling that Parfitt (1983) suggested, “According to the quantum concept of bone remodeling proposed by Frost, bone formation in the adult human normally occurs only at sites where bone resorption has recently been completed” (p.171).  Referring to bone loss due to age, “It is obvious that for bone loss to occur the rate of total body bone resorption must exceed the rate of total body bone formation. In terms of the quantum concept, this imbalance must be focal and must apply to the average remodeling cycle on nay surface that is losing bone” (Parfitt, 1983, p.328).

Sometime between the ages of 30 and 40 human bone mass reaches its’ peak, and after that bone mass decreases with age (Heaney, 1983, p.333). With age related bone loss, “The decline is particularly rapid in women in the 5-15 years following menopause. Reduction in bone mass comes about through bone remodeling…” (Heaney, 1983, p.333). “Osteoclasts are responsible for the following two major functions: {1} the remodeling of bone to form the adult skeleton in conjunction with osteoblasts, and {2} the maintenance of serum calcium under the control of parathyroid hormone” (Jowsey, 1977, p.74).

Dietary histories pertaining to metabolism needs to have an average for the intake of phosphorus and calcium (Jowsey, 1977, p.87). Jowsey (1977) also writes, “… also some evaluation of other substances that affect mineral metabolism, such as vitamin D intake and exposure to the sun” (p.87). Dairy products and leafy vegetables contain calcium (Jowsey, 1977, p.87), and usually these products are in a human’s daily diet. When concerning the mineral calcium, “The recommended calcium intake is 800 mg per day for an adult” (Jowsey, 1977, p.89). Jowsey (1977) suggests, “Calcium balance generally reflects bone metabolism. In general, a positive balance represents an increase in bone mass, whereas negative balance implies a loss of bone tissue” (p.90).

HISTORY

Diagnosis

All of the mentioned bone abnormalities are measured with some form of radiography. Also, fractures in bone disorders usually help bring the physician’s attention to the bone, and can also lead to diagnosing a bone disorder. Levels of minerals, vitamins, and hormones affect the bone density by resorbtion and bone formation. Lack of or in excess of these factors, will lead to abnormalities in the bones. In some instances, one bone disease can lead to another, “Since the majority of patients with rickets or osteomalacia have developed a mineralization failure as a result of a lack of adequate levels of calcium in the serum, stimulation of the parathyroid glands must be expected. This can occur before, during, or after the development of osteomalacia” (Jowsey, 1977, p.192). Bone abnormalities are not difficult to diagnose; however, the intake of food does affect bone density as mentioned earlier, but somehow physicians still claim it is fine to eat before a bone density scan (RadiologyInfo, n.d.).

For every research project, there is a different method that suits the research data best. The two main categories of research designs are qualitative and quantitative methods. Qualitative deals mostly with groups and categories, while quantitative covers the numerical data or ratio. Under both qualitative and quantitative methods, there are different types of studies that a researcher can use. Qualitative method is best explained as, “The Discovery of Grounded Theory, qualitative researchers have been debating whether the purpose of qualitative research should be to develop new theory, verify existing theory, or both” (Bailey, 1997 p. 134).

Chapter III Research Method

COLLECTING DATA

Techniques

            Bailey (1997) wrote, “Sometimes the research method dictates data collection techniques” (p. 94). Different techniques to gather data are observation, interview, written questionnaire, record and artifact review, hardware instrumentation, test, measures, and inventories. For some collecting data techniques there are a qualitative and a quantitative method. Observations could consist of, “…human subjects, videotape recordings of subjects or events, or nonhuman items such as pieces of equipment” (Bailey, 1997 p. 94-95). When using qualitative observations, “The researcher keeps field notes of everything observed that might be remotely useful in the study, such as the environment, the participants’ appearance and manner, routines, unusual events, human groupings at specific times, and so on” (Bailey, 1997 p. 95). Bailey’s (1997) description of record and artifact review was, “Review of written records may be a means of data gathering in many types of research, including experimental, ethnographic, historical, and case study designs” (p.101). Examples of some of the written documents the researcher reviews are medical records, case conferences, letters, speeches, articles, books, notes, newsletters, and newspapers (Bailey, 1997 p.101). For another data collection method, hardware instrumentation is described as, “Physical or mechanical instruments that provide a valid and reliable measurement are usually more desirable in experimental research than the subjective feedback given by subjects” (Bailey, 1997 p.101-102). This type of data collection would be used for experiments or variables that cannot be measured or seen without technical support. Tests, measures, and inventories test the “Variables that can be measured be these written means include psychological factors, cognitive abilities, perceptual motor skills, child development stages, prevocational skills, vocational interests, personality factors, attitudes, and values” (Bailey, 1997 p. 102). When collecting data, there are many different methods, but Bailey (1997) points out, “In summarizing and interpreting the data gathered, the researcher must use logical analysis and try to be as objective as possible” (p.101). Collecting useful data is important for the research, and these methods are just a few of the techniques to do so.

RESEARCH METHOD

Qualitative

            For researching if eating before a bone density scan could affect the results, the qualitative research design is the most appropriate. The issue with bone density scans is there are limitations to the patient. For example, before the patient has a bone density scan, he or she cannot take calcium pills or vitamins, because those could affect the results of the scan. There have been studies done that prove these pills affect the bone density results. Food consists of some of the same ingredients in the calcium pills and vitamins. So, in theory, food should also affect the results of a bone density scan. For this research study, a case method research design fits the criteria. The case method research design is, “…studying an individual person, program, or institution” (Bailey, 1997 p. 138). The subject needs to have a bone density disease, such as osteoporosis, in order to be useful in the study.

DATA

Validity

            The data collected from the patients needs to be precise and valid, or else the research is useless. Two methods would be helpful with this research study such as record artifact review and hardware instrumentation. The record artifact review gives the medical history of the subject. Medical history is important for the researcher to be familiar with, because the subject will need to have a bone density disorder. Also, the researcher will need to know information about metabolism in the bones to know what types of food can affect the bone density. The hardware instrumentation is necessary in order to do the DEXA exam. Since there are a few different exams to perform on each part of the skeleton depending on where there is low density, will depend on what type of exam is used.

ANALYZING

Organizing the data

            The next step after testing and collecting the data is analyzing the information gathered. Bailey (1997) explains, “These types of studies often generate large amounts of descriptive, nonquantifiable data that need to be organized and synthesized in a useful manner” (p. 158). The types of studies Bailey is referring to are the methods used for collecting data in qualitative research, and “The style of qualitative research and data analysis method you choose will depend on whether your ultimate goal is to inform policy, describe situations in a novel manner, or generate theory” (Bailey, 1997 p. 159). There is a process to analyze the data collected. First the researcher must organize and describe the data. Bailey (1997) gives tips for the researcher organize the data:

First organize the data by reading through and making sure that they are all present, filling in any gaps by returning to the field, if necessary. Get a feel for how much data there are, including transcriptions of interviews, field notes from observations, memos to yourself, formal documents, descriptions of artifacts, and son on. (p.159)

Reading the documents several times will help with indexing the data completely (Bailey, 1997 p.160). Reading all of the data collected after testing the bone density on patients, the data will be clearer and will make analyzing the data easier. The documents that need to be reviewed are the field notes from observation and the subject’s medical history. Bailey (1997) mentions that instead of writing notes in the margins of the documents that the researcher can also write on index cards. (p. 160) The descriptions of the index cards is:

The back of each index card should be coded in multiple ways: the source of the information (e.g., interview transcription, treatment plan, observation notes) by page and paragraph number; the particular episode during which the information was collected (e.g., interview with rehabilitation director, team meeting); the type of respondent (e.g., staff person, administrator); the site where the information was gathered (e.g., school classroom, rehabilitation clinic, supervisor’s office). (Bailey, 1997 p. 160).

After organizing and coding the information from the data collection, the index cards must be categorized into different sets of information. (Bailey, 1997 p. 160) Another method for gathering the data collected is a data display, and Bailey (1997) quotes Miles and Huberman (1994), “Data display is an organized compressed assembly of information that permits conclusion drawing and action… Looking at displays helps us to understand what is happening and to do something- either analyze further or take action- based on that understanding” (p.168). Using displays to graph the difference, if any, between eating and not eating before a bone density scan, will be easy to read and draw a conclusion from. Along with drawing a conclusion from the data collected, the conclusion must be verified, and “Verification may be as brief as a quick recheck of the data to confirm a current idea, or as lengthy as a thorough review of data among colleagues or an attempt to replicate a finding in another data set” (Bailey, 1997 p.169). Verifying the data for this research project would include going over the documents to make sure nothing was missed or misinterpreted. All of these steps will conclude in finding answers to the research if eating before a bone density scan affects the results.

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