Case Study

A 60-year-old woman with low back pain and waddling gait.

A 60-year-old woman comes to your office with complaints of low back pain, which is causing progressive difficulty in walking. The pain has graduallyincreased since the onset of menopause five years ago. This discomfort is especially noticeable after prolonged sitting.

Social history reveals that the patient has been a housewife since her marriage 38 years ago. Her husband, who is in good health, owns and operates a small retail shop in their home. The patient has been making jewelry for sale in her husband's shop and as a hobby for about 35 years. They have two adult sons who are in good health.

The patient denies a personal or family history of kidney disease, hypertension, diabetes mellitus, or cardiovascular disease; she also denies history of back trauma or weight loss. She has smoked one to two packs of cigarettes a day for the past 40 years. She does not take estrogens, calcium supplements, vitamins, or other medications.

On examination you find a thin female with a slightly stooped posture and a waddling gait. Blood pressure is 120/70. Her teeth have a yellow discoloration above the crown, and her fingernails are stained with nicotine. She is anosmic on cranial nerve examination. Results of cardiovascular and abdominal examination are normal. The lower lumbar spine is tender to percussion, but the patient does not complain of pain on straight leg raising. Her deep tendon reflexes are intact, and the remainder of the physical examination, including neurological testing, is normal. Sensation and strength are normal in legs and feet. Range of motion is normal in hips and knees.

Initial laboratory data include a urinalysis showing 3+ proteinuria and glycosuria. Blood urea nitrogen (BUN), creatinine, and albumin levels are normal. Radiographs of the pelvis and lumbosacral spine reveal pseudofractures and other evidence of severe osteomalacia and mild osteoporosis. There are no osteolytic or osteoblastic lesions.

The patient maintains a jewelry fabricating and engraving area in the basement of her home where she uses abrasive grinders, engraving equipment, soldering tools, and various raw materials. She does not use a dust mask but does wear a face shield when operating the grinder. The work area is dusty, with only two small windows near the top of one wall capable of providing ventilation. There is no local or general mechanical exhaust system. She admits to smoking and eating in the work area. The patient and her husband also tend a small garden in the backyard in which they grow vegetables for the table. A nearby wastewater treatment plant provides free fertilizer, which her husband applies to the garden every few weeks. The garden is irrigated with water from a municipal well.

Initial Check Questions

1. What should be included on the patient's problem list?
2. What are the potential sources of cadmium exposure for this patient?
3. Why is the patient described in the case study at increased risk of cadmium toxicity?
4. Is the patient's husband also at increased risk? Explain.
5. Could diet play a role in the condition of the patient described in the case study?
6. If you suspect cadmium poisoning, what other questions could help gauge the extent of exposure to the patient described in the case study?
7. What tests would be helpful in further evaluating the patient or in supporting a diagnosis of cadmium toxicity?
8. Assuming the patient described in the case study has cadmium toxicity, what would be a likely urinary cadmium level?
9. What treatment will you recommend for the patient described in the case study?
10. Should the patient's neighbors be evaluated for cadmium or other heavy-metal exposure? Explain.

Initial Check Answers

1. The patient's problem list includes
   • back pain,
   • glycosuria,
   • proteinuria,
   • severe osteomalacia and mild osteoporosis pseudofractures, and
   • yellow discoloration of the teeth.

   All of these problems are consistent with chronic cadmium toxicity. The patient is also a smoker. Chronic cadmium exposure primarily affects the bones and kidneys and possibly the lungs. Renal dysfunction in this patient is indicated by the laboratory findings. The stooped posture, waddling gait, lumbar pain, and pain induced by spinal percussion are the result of skeletal changes and deformities.

   The information for this answer comes from section: “What Health Effects Are Associated with Acute High-dose Cadmium Exposure?”

2. Potential sources of cadmium are
   • cadmium fume (cadmium oxide) generated by use of gold and silver solders during jewelry fabrication,
   • cadmium dust produced in smoothing jewelry with abrasive grinding or in engraving cadmium-plated surfaces,
   • food and cigarettes in the workplace contaminated by cadmium-containing particulates and dust,
   • cigarette smoke, and
   • food grown in soil contaminated with cadmium-containing fertilizer obtained from the wastewater treatment plant

   The information for this answer comes from section: “Where is Cadmium Found?”

3. Risk factors are due to not only increased opportunity for cadmium exposure, but age and nutritional status as well. The patient's hobby, jewelry fabrication, may provide low to moderate chronic cadmium exposure. Lack of respiratory protection, poor ventilation, and poor hygiene in the work area increase the amount of her exposure. One of the major sources of cadmium exposure in smokers is inhaling cadmium from cigarette smoke. The amount of cadmium ingested from the vegetables grown in her garden is unknown, but sludge from wastewater treatment plants contains significant levels of cadmium. Factors that may enhance cadmium absorption from the gut are age and certain dietary deficiencies.

   The information for this answer comes from section: “What Are Routes of Exposure to Cadmium?”

4. Yes, the patient's husband also may be at increased risk of cadmium toxicity because of increased opportunity for exposure, although his risk is probably less than his wife's. The husband is exposed to cadmium by eating food from the contaminated garden and by inhaling environmental tobacco smoke from his wife's cigarettes (even more so if he smokes as well). In the basement work area, he may encounter cadmium fumes and dust as a result of his wife's hobby. He also may be exposed to the cadmium on his wife's clothing and skin if she does not shower and change clothes before leaving the work area.

   The information for this answer comes from section: “What Are Routes of Exposure to Cadmium?”

5. Yes, diet could play an important role in the patient's condition, both for what it contributes and for what may be missing from it. For example, the homegrown vegetables from the garden, particularly leafy vegetables, and animal liver or kidney and shellfish could be contributing to her cadmium burden. If her diet is deficient in calcium, or if she is postmenopausal, she may be absorbing cadmium more efficiently.

   The information for this answer comes from section:  “What Factors Increase the Risk of Developing Disease from Exposure to Cadmium?”

6. Most of your questions will probably center on the patient's hobby/home industry because it is the greatest potential source of cadmium exposure.

   Typical Environmental History questions.

   1. What types of materials and metals are used in making jewelry, and what are the ingredients of all composite products? When the patient then asks the doctor where this information can be obtained, the primary care physician must know where to refer the patient. The Material Safety Data Sheet (MSDS) and other chemical labeling of products used are ideal resources of chemical information. Employers are required to have a chemical safety plan and a hazard communication program in place to comply with mandated OSHA standards. However, the woman in question since she does not work outside the home would not be covered by such regulations. Other resources, such as those listed in the appendix, can provide additional guidance regarding other standards and regulations concerning cadmium.

   2. On a weekly basis, how many hours are spent fabricating jewelry in the basement?
   3. What type of face shield is used?
   4. Why is respiratory protection not used during grinding and soldering operations?
   5. Is the work area kept clean and free of dust? If so, how?

   6. Does the patient wash her hands before eating in the work area? Have procedures been developed to keep food and cigarettes from becoming contaminated by dust and particulates?

   7. Does she shower and change her clothes before leaving the work area?

   It is also important to investigate smoking habits.

   The information for this answer comes from section: “Clinical Assessment – History and Physical Examination.”

7. The most useful diagnostic test for cadmium exposure is a 24-hour urinary cadmium excretion standardized for creatinine. â₂-microglobulin levels, in the face of elevated cadmium excretion, will aid in evaluating subclinical renal dysfunction. Urinary protein and glucose tests may also be helpful in evaluating the patient. You could also measure blood cadmium levels.

   The information for this answer comes from section: “Clinical Assessment – Laboratory Tests.”

8. The patient is experiencing renal dysfunction, as evidenced by the 3+ level of proteinuria and glycosuria. When proximal tubular damage occurs, cadmium excretion can result from two sources: breakdown of the tubular epithelium and decreased reabsorption. Under these conditions, urinary cadmium levels are likely to be markedly increased and no longer reflect body burden. Exposed workers can excrete several hundred micrograms of cadmium per gram of creatinine, The geometric mean for urinary cadmium levels in the general population over age 21 is 0.210µg/gm creatinine (CDC, 2005). The patient therefore would be expected to have a urinary cadmium level of several hundred micrograms of cadmium per gram of creatinine, depending on her most recent exposure.

   The information for this answer comes from section: “Clinical Assessment – Laboratory Tests.”

9. There is no effective treatment for cadmium toxicity. Chelation therapy has no role in cases of cadmium poisoning. Removal from the source of exposure and patient education to significantly reduce exposure are important, particularly before the condition has progressed to irreversible renal dysfunction. Supportive measures to alleviate symptoms should be provided such as supplementation with calcium and vitamin D if wasting or bone disease is present.

   The information for this answer comes from section “How Should Patients with Cadmium-related Diseases Be Treated and Managed?”

10. The neighbors should be evaluated and educated on the health dangers associated with exposure to high levels of cadmium. Even if they do not use the fertilizer from the wastewater treatment plant or water from the same irrigation source, runoff from the patient's land may contaminate their soil or well water. Consultation with the local or state health department is advisable if a potential public health hazard exists.

    The information for this answer comes from section: “What Factors Increase the Risk of Developing Disease from Exposure to Cadmium?”