Environmental exposures worsen untreated diabetes
Heavy metal exposure from a patient's well water accelerated multisystem damage associated with diabetes.
Environmental exposures worsen untreated diabetes
Mrs. S, a 67-year-old patient, presented for her first visit to a primary care provider in more than 10 years. She appeared generally unwell. She stated she was told years ago that she was diabetic and said, “they wanted me to take medicine.” But she refused and insisted on “taking care of it naturally.”
Since Mrs. S never returned for further care, she was lost to follow-up. She came into the office because she was too tired to do her household chores. She had lost weight and was “really afraid there's something wrong.”
Mrs. S lived in a rural area and was a widow with three grown children who resided too far away to see her regularly. “I don't want to bother them,” she stated when asked if her family knew she was ill.
The only other health history she relayed was a broken tibia three years ago. “I just slipped, and it broke,” she stated. A local emergency department casted the break and she returned there requesting the cast be removed six weeks later.
Mrs. S's initial assessment showed a height of 4'11” and weight of 98 pounds. Her blood pressure was 147/89 mm/Hg, pulse 87 BPM, and respirations 16 per minute. Her posture was kyphotic. Breath sounds were clear bilaterally, and heart rhythm was regular with a 3/6 systolic murmur.
Her skin was dry and flaking. She had 2+ pitting edema of her ankles and feet. Nail beds and mucous membranes were pale.
Laboratory testing revealed significant hyperglycemia with an HbA1c of 9.8 %, a serum creatinine of 4.2 mg/dL, and hemoglobin and hematocrit of 8.2 g/dL and 25%, respectively. There is 310 mg of micro albumin in her urine, as well as 5 to 10 RBCs/HPF. Her serum calcium was 6.9 mEq/dL and phosphorous was 5.7 mg/dL.
Mrs. S denied allergies and was taking no medication. She did, however, routinely drink a ‘tea' that she brewed herself from the leaves of a blueberry bush.
With the recent history of a low trauma fracture, a bone mineral density (DEXA) scan is done. The results indicate severe osteoporosis with a T-score of -4.2 SD.
In completing the history and assessment of Mrs. S., the healthcare provider asked for more details of her home life. In addition to the blueberry leaf tea, Mrs. S stated she does other gardening and cans several kinds of vegetables from her garden. Her water source is a private well that she has used for the 20 years she has lived in her home.
Knowing that the community was located in an area with a history of extensive zinc mines, the healthcare provider next ordered a 24-hour urine collection to screen for heavy metals. Mrs. S's cadmium level was 37 mcg/L (normal range = <5 mcg/L).
Mrs. S. lived in an area known as a “superfund site.” The area is one of many across the United States that have been designated by the Environmental Protection Agency (EPA) as regions severely polluted with highly toxic substances. In this case, the region used to be known for its extensive underground mining industry. The mines were deep enough that they were often below the level of ground water.
During periods of active mining, the shafts were kept dry by massive pumps. As the ore was gradually depleted, the mines were abandoned, and refilled with water. Since the soil and the ground water were in direct, constant contact with the depleted mine shafts and waste piles -- or “tailings” -- toxic heavy metals including cadmium accumulated.
The well water and the blueberry leaf tea that Mrs. S. had been using contained high levels of cadmium. This toxic heavy metal accelerated the multi-system damage that had been occurring due to her diabetes, including decreased renal function and osteoporosis.
The only known treatment for any heavy metal toxicity is chelation. A substance with high affinity to the metal is introduced into the system. There it binds it into a complex that is eliminated through the kidneys. No large trials exist to validate the safety or efficacy of this process, but the use of ethylenediaminetetraacetic acid (EDTA) is generally agreed upon as the chelating agent.
There is no standard timeframe to determine how long therapy must continue, and little evidence to support reversal of end-organ damage. Patients who smoke or who are iron-deficient will have higher concentrations of cadmium than others.
Sherril Sego, FNP-C, DNP, is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women's health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas.
- Sigel A, Sigel H, Sigel RKO (Eds). (2013). Cadmium: From toxicity to essentiality. Metal Ions in Life Science. (Vol. 11, pp.395-413). New York, NY: Springer.
- Agency for Toxic Substances and Disease Registry. (2011). “Cadmium.” Retrieved 18 April 2014 from http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=15
- Bernhoft RA. The Scientific World Journal. 2013; doi: http://dx.doi.org/10.1155/2013/394652.
- Environmental Protection Agency. Cleaning up the nation's hazardous waste sites. Retrieved 18 April 2014 from http://www.epa.gov/superfund/sites/index.htm
- Smolders E. Int J Occup Med Environ Health. “Cadmium uptake by plants”. 2001. (Vol. 14-2: pp. 177-183).