Temporary laboratories, prion resistance to formalin, lipid panels, and mixed casts

July 1, 2002
Edited by Daniel M. Baer, M.D.

Lab in a trailer

Q Our hospital is undergoing renovations. As a result, the hospital laboratory will need to be relocated. Space limitations in our facility make it necessary to find a temporary location for our laboratory services. Are you familiar with any vendors who provide a mobile laboratory on a lease basis, either equipped or providing basics such as draw stations, counter tops, refrigeration units, running water, and appropriate alarm systems for refrigeration? Our thinking has focused on trailers, modular units, etc. that could be set up and operated from a parking lot site. 

A: Mobile medical facility facilities have been custom-built for such applications as traveling clinics, blood donor collection vans, and military or disaster medical units. The emphasis is on mobility, so they are constructed as vans that can move from place to place.

Although not applicable to your need, a small, self-contained laboratory cart that can provide point of care testing within a hospital or clinic, has been described.1 It contained a small chemical analyzer, blood cell counter and coagulation instrument. It could not handle the needs of an entire hospital.

Temporary laboratories have been constructed in trailers or modular buildings, but all, to my knowledge, have been constructed by the owner, and were not leased.

There are several things to consider:

Location is important. The laboratory should be close to high use, critical need areas such as emergency room, ICU, and operating rooms. A site outside of the hospital building might require a change in the CLIA license and could lead to

A possible solution is to put lab administrative functions in a temporary building. Find a small space in the hospital building for essential laboratory functions such as a drawing station and STAT laboratory, which would perform only high-volume critical care tests. Send low-volume non-STAT tests to a referral laboratory or arrange with a nearby laboratory to temporarily perform these tests.

As an alternative, it might be possible to move a business office or other nonclinical activity to a temporary building outside of the hospital, and allow the laboratory to occupy its space while construction is taking place.

If the lab must leave the hospital building during the construction, rent a modular building and put existing equipment in it. Keep in mind that you will probably need to provide plumbing, extra electrical power, and air-conditioning to take care of the large amount of heat-generating equipment in the laboratory.

Daniel M. Baer, M.D.
Professor Emeritus
Department of Pathology
Oregon Health and Science University
Portland, OR


1. Travers EM, Wolke JC, Johnson R, Brown L, Lijewski R, Pinkos A, Trost A. Changing the way lab medicine is practiced at the point of care. Medical Laboratory Observer. Vol 26, No 7, July 1994, pp 33-40.

Prion resistance to formalin

Q: I am looking for an article that talks about the resistance of prions to
formalin. I have been told that tissues and instruments used with patients with Creuttzfeldt-Jakob Disease (CJD) must be disinfected in a special way.

A: Safety protocols relating to potentially prion-infected materials have recently been published by both the Centers for Disease Control and the World Health Organization. The CDC publication is entitled Biosafety in Microbiological and Biomedical Laboratories, 4th edition;1 the WHO publication is entitled WHO Infection Control Guidelines for Transmissible Spongiform Encephalopathies.2 Both reports are available via the Internet and address concerns regarding various decontamination protocols and the effects of fixatives. These publications discuss the risks associated with prions in terms of procedures, occupational exposures, transport of specimens, waste disposal, and instrument and work space decontamination. They also provide biosafety level recommendations for research and clinical laboratories based on their degree and type of exposure. In addition, the WHO publication gives details relating to gravity displacement versus porous load autoclaves, chemical disinfectants, and precautions regarding the possible combinations of chemical and physical means of decontamination. Readers are encouraged to refer to these publications for detailed instructions which they may apply to their specific needs. You can find additional information on the CDC website by searching on CJD.

Randall Nixon, M.D., Ph.D.
Assistant Professor
Department of Pathology
Oregon Health Sciences University
Portland, OR


1. www.cdc.gov/od/ohs/biosfty/bmbl4/bmbl4s7d.htm

2. www.who.int/emc_documents/tse/whocdscsraph2003c.html

Lipid panels

Q: I have a question regarding acceptable reference values for ratios in lipid panels. The two I am interested in are total cholesterol/HDL cholesterol ratio and LDL cholesterol/HDL cholesterol ratio. The NCEP was silent on these ratios when I last looked into the subject a few years ago. I recall this was because of both analytical and biological variation in HDL measurement. A small change in HDL could correspond to a significant change in the ratios. I saw that the Hanes II study recommend a T chol/HDL ratio

A: The question that you ask concernning the use of lipid/lipoprotein ratios (i.e., total
cholesterol/HDL cholesterol, LDL cholesterol/HDL cholesterol), is a very common one. The National Cholesterol Education Program (NCEP) II, II, or III has never mentioned the use of the ratios. The most recent NCEP III report1 focuses on a lower LDL cholesterol (LDL C) therapeutic goal ( (HDL-C) of (CHD). The use of the ratios was never discussed in this report. 

No doubt many clinical studies show that the use of ratios was always statistically superior to nonratios when comparing different population outcomes (fatal or nonfatal myocardial infarctions). However, when applied on a single patient basis, the use of nonratios was always advocated. 

An example of when the use of ratios can be misleading is seen in the following Case A: Before treatment, the total cholesterol (TC) (300 mg/dL)/HDL cholesterol (60 mg/dL) = ratio of 5.00. After treatment, the total cholesterol (200 mg/dL), / HDL cholesterol (40 mg/dL) = ratio of 5.00. The ratios did not change; thus, which is the better profile? 

Take Case B: Before treatment the TC (300 mg/dL)/HDL-C (60 mg/dL) = ratio of 5.00. After treatment the TC (160 mg/dL)/HDL-C (32 mg/dL) = ratio of 5.00. What do you tell the patient? Do you tell the patent that his/her TC is now fine, but the ratio did not change, or the ratio is fine, but the HDL-C is abnormal? This can be very confusing to the patient. 

In short, it is not recommended that you use the ratios when assessing a patients risk or for goal setting or when monitoring the intervention process. The use of ratios should be left to population studies and not applied to patient care. 

Herbert K. Naito, Ph.D., MBA
Chief, Ancillary Testing and Satellite Facilities
Louis Stokes Cleveland VA Medical Center
Cleveland, OH


1. Adult Treatment Panel III. Executive summary of the third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation, and treatment of high blood cholesterol in adults. JAMA: 2001;285(19): 2486-2496. 

Mixed cellular casts

Q: What is the recommended procedure for reporting mixed cellular casts? Does the percentage of the different cellular components influence the reporting and clinical significance of the finding?

A: Each type of cast seen in a given urine sediment should be identified and graded separately. They are generally graded or reported as the average number seen per low power (10x) field. If mixed casts are present, they should be reported as mixed casts and the components described as completely as possible. An example might be, 0-2 mixed casts (red cell and epithelial cell), or two to five mixed casts (waxy and red cell). 

According to Haber the term mixed cast should be used only to describe casts with at least two distinct portions.1 Mixed casts are further described based on the composition of each of the portions. Therefore, if a cast is made up of a portion containing white cells, and another portion containing epithelial cells, it might be described as mixed cast (white cell and epithelial cell). In general, the reporting of mixed cast is used only for casts consisting of two distinct portions or types of different composition and appearance. The type of mixed cast should be described as completely and accurately as possible. Therefore, a cast consisting of a waxy portion and a granular portion should be reported as mixed cast (waxy and granular). Conversely, a cast consisting of a hyaline matrix with white cells evenly distributed throughout the cast should be reported as a white cell cast or possibly hyaline white cell cast. However, if the cast consists of a distinct hyaline portion and another distinct portion containing white cells, it should be reported as mixed cast (hyaline and white cell). 

Clinically, such descriptions may be useful. A mixed cast (red cell and white cell) might suggest that two different portions of the nephron have been injured. The red cell cast often implies glomerular injury, while white cells are more consistent with interstitial injury. 

Reporting the percentage of each cellular component within a mixed cellular cast might be overly ambitious, however. In general, you should be as descriptive as possible while maintaining accuracy.

Karen M. Ringsrud, MT(ASCP)
Department of Laboratory
Medicine and Pathology
University of Minnesota Medical School
Minneapolis, MN


1. Haber MH. Urine Casts: Their Microscopy and Clinical Significance,ed 2. Chicago, American Society of Clinical Pathologists, 1976, p. 81.

Daniel M. Baer is professor emeritus of laboratory medicine at Oregon Health and Science University in Portland, OR, and a member of MLOs editorial advisory board.

© 2002 Nelson Publishing, Inc. All rights reserved.