Case Study 1
AIDS (Acquired Immunodeficiency Syndrome)
The patient, a 30-year-old homosexual man, complained of unexplained weight loss, chronic diarrhea, and respiratory congestion during the past 6 months. Physical examination revealed right-sided pneumonitis. The following studies were performed:
Complete blood cell count (CBC), p. 174
Hemoglobin (Hgb), p. 259 12 g/dL (normal: 14-18 g/dL)
Hematocrit (Hct), p. 256 36% (normal: 42%-52%)
Chest X-ray, p. 1014 Right-sided consolidation affecting the posterior lower lung
Bronchoscopy, p. 587 No tumor seen
Lung biopsy, p. 738 Pneumocystis jiroveci pneumonia (PCP)
Stool culture, p. 855 Cryptosporidium muris
Acquired immunodeficiency syndrome (AIDS) serology, p. 297
p24 antigen Positive
Enzyme-linked immunosorbent assay (ELISA) Positive
Western blot Positive
Lymphocyte immunophenotyping, p. 306
Total CD4 280 (normal: 600-1500 cells/L)
CD4% 18% (normal: 60%-75%)
CD4/CD8 ratio 0.58 (normal: >1.0)
Human immune deficiency virus (HIV) viral load, p. 297 75,000 copies/mL
The detection of Pneumocystis jiroveci pneumonia (PCP) supports the diagnosis of AIDS. PCP is an opportunistic infection occurring only in immunocompromised patients and is the most common infection in persons with AIDS. The patient’s diarrhea was caused by Cryptosporidium muris, an enteric pathogen, which occurs frequently with AIDS and can be identified on a stool culture. The AIDS serology tests made the diagnoses. His viral load is significant, and his prognosis is poor.
The patient was hospitalized for a short time for treatment of PCP. Several months after he was discharged, he developed Kaposi sarcoma. He developed psychoneurologic problems eventually and died 18 months after the AIDS diagnosis.
Critical Thinking Questions
1. What is the relationship between levels of CD4 lymphocytes and the likelihood of clinical complications from AIDS?
2. Why does the United States Public Health Service recommend monitoring CD4 counts every 3 to 6 months in patients infected with HIV?
Case Study 2
Multiple Sclerosis (MS)
A 35-year-old woman was active in jogging and horseback riding until 1 year ago. During the past year she began to notice severe weakness and paresthesias in her legs. Her gait became unsteady, and she developed loss of vision in one eye. A neurologist suspected multiple sclerosis (MS) and ordered the following studies:
Routine laboratory work Within normal limits (WNL)
Lumbar puncture with cerebrospinal fluid (CSF) examination, p. 651
Immunoglobulin (Ig) G index 0.8 (normal: 0.3-0.7)
IgG determination 20% (normal: 0%-11% of total protein)
Oligoclonal bands Present (normal: none)
Evoked potentials (EPs), p. 562
Visual-evoked potentials Abnormal latency
Auditory brainstem-evoked potentials Normal
Somatosensory-evoked responses Abnormal latency
Magnetic resonance imaging (MRI), p. 1106 Plaques indicative of multiple sclerosis
The wide variety of symptom manifestation often makes MS difficult to diagnose; however, the above studies clearly identified MS as the patient’s problem. The CSF study results were classic for the diagnosis of MS. The abnormal latency demonstrated on the EP studies was the result of the demyelination process of MS. MRI revealed plaques indicative of MS.
The patient was given prednisone to decrease the inflammation and associated edema of the myelin sheath. When remission occurred, she was instructed about factors that exacerbate, prevent, or ameliorate symptoms.
Critical Thinking Questions
1. Why were the results of the CSF study classic for the diagnosis of MS?
2. What is latency, and why is it increased in MS?
A 64-year-old physician recently noted excessive tiredness throughout the day. He also complained of right hip/buttock pain. This prompted laboratory testing. On physical examination he was found to have an elevated heart rate (100 per minute) and appeared pale.
Routine laboratory data
Normal except as indicated below
CBC, p. 174
WBCs = 24,000 (normal: 5000-10,000)
Hgb = 8.2 (normal: 14-18 g/dL)
Hct = 25 (normal: 42%-52%)
Differential indicates increase in mononuclear cells
Albumin, p. 424
2.8 g/dL (normal: 3.5 to 5)
Protein electrophoresis, p. 424
Spike in beta 2 microglobulin
Beta-2 microglobulin, serum, p. 362
4.2 g/mL (normal: 0.70-1.80 mcg/mL)
Multiple myeloma, urine, p. 911
4000 mcg/L (normal: less than 300 mcg per mL)
Laboratory cytogenetics, p. 161
Deletion noted in chromosome 13
Multiple genetic translocations noted
X-ray, right hip, p. 1006
Multiple radiolucent spots in the right ileum and femur
This patient has marked anemia associated with elevated mononuclear (plasma) cell count. The RBCs are reduced because of the tumor burden affecting the marrow’s ability to make RBCs. Elevated levels of beta-2 microglobulin are noted, compatible with multiple myeloma. Laboratory cytogenetics supports the finding. The radiolucent changes noted in the right hip are the cause of his pain. The physician received aggressive chemotherapy that was successful in reducing his protein markers for 2 years. Unfortunately, he relapsed. He required further chemotherapy and bone marrow transplantation. He is now doing well and is quite active.
Critical Thinking Questions
1. What other diseases are associated with an elevated white blood cell count?
2. What are the risks of the disease affecting the patient’s bones?
3. What is the name of proteins commonly in the urine of patients with multiple myeloma?
4. Why was the albumin abnormally low?
5. What tests will be used to monitor this man’s disease?