Module 9 Exam Flashcards
9.1 2. Plasma glucose concentration may be used for diagnosing the prevalence
of diabetes mellitus in a population. In trials on populations of people believed to
be healthy and diabetic patients the test has a clinical sensitivity of 60% and a
clinical specificity of 90%.
What is the most cost effective way, from a clinical point of view, to use this test?
a) To screen a healthy population for disease.
b) To assist in the diagnosis of people with the symptoms of diabetes.
c) To rule out the likelihood of diabetes in people thought to be healthy.
d) The test is of no clinical use at all.
C a healthy person is least likely to give a false result. Diabetics give 40% false negative results. No good for diagnosis or health screens. Too many are missed.
9.1 4. Serum sodium result was 300 mmol/L (healthy range is 135-145, a serum result of
300 mmol/L is lethal).
What is the most likely source of this error?
a) Sample is urine, not serum.
b) Sample was contaminated.
c) Method used measures also potassium but reports it as sodium.
d) The technologist made a transcription error on the report.
A. B is less likely as it would have to be a gross contamination and the modern systems are designed to reduce this to a minimum. Contamination at this level would not be seen from an IV fluid. Potassium levels are about 3% of sodium in plasma/serum. Transcription errors of this magnitude are almost impossible even with untrained people.
9.1 5. Serum specimens taken during the afternoon and evenings at the Clinic were
stored until shipped to a private reference laboratory at 11 pm. The serum was
separated out at the reference laboratory. All the potassium results were over 6
mmol/L. (3.5-4.5)
Which of the following are the most likely explanation(s) for these results?
a) The serum was not separated from the red and white blood cells in a timely
manner.
b) The samples were stored at room temperature.
c) The samples were stored in the refrigerator at 4 o C.
d) The potassium reference range is wrong.
A and C. A because left on the clot cells begin to die and lyze. In the refrigerator metabolism is slowed so C is also valid. Blood is quite stable at room temperature for many chemicals for an hour or more.
9.1 6. At a shopping mall an entrepreneur was carrying out serum cholesterol tests on
those willing to pay a fee for the service. One man received a high (abnormal
unhealthy) value. He had his serum cholesterol checked at the lipid clinic at St.
Michael’s Hospital and the value was in the healthy range.
Which of the following are most likely reasons for this difference?
a) The vendor is subject to no quality control.
b) The vendor may have a conflict of interest.
c) St Michael’s Hospital laboratory has a conflict of interest.
d) Serum cholesterol is very variable. Source based on article in Association of
Clinical Biochemists’ (UK) news
A. In this case which was taken from a published report the vendor sold cholesterol lowering products and so had a conflict of interest hence B was also likely but this information was not given
9.1 7. You send a hair sample to Acme Foothills Laboratory and also to the Florida Sun
Laboratory. The Acme laboratory reports that the sample is deficient in many
minerals and vitamins. The Florida laboratory states that the sample has very high
zinc content.
How might you best tell which one is telling the truth?
a) Send the same samples again but under a different name.
b) Talk to the patient, does he use Head and Shoulders, a zinc containing
shampoo?
c) Ask the laboratory staff about the methods used.
d) Ask the laboratory staff about external quality assurance procedures.
D is the best answer. If the external references are not credible then the laboratory could well be incompetent or fraudulent but A and C may help to show incompetence or fraud. All of the answers have some validity.
9.1 8. A laboratory offers the cheapest test menu in the area, has the fastest time to
report results, and offers valuable incentives to users of their services. Results
always come back in the middle of the usual healthy reference ranges.
Which of the following is the most likely explanation for this performance?
a) The laboratory is heavily automated and computer controlled.
b) It is to be expected that results will very often be in the middle of the normal
range.
c) The samples are not tested at all and the results are made up.
d) The laboratory uses unique methods which are better than those used by the
competition.
C. This is blatant fraud. A and D do not explain why the results are the same. B is only possible if the population is carefully selected to be “normal”. Initially this was a white 70 kg young adult male population that was used to set up the first reference ranges. Often these men were soldiers in World War II, medical or nursing students.
Case 9.2 1. A 30-year-old elite woman distance runner was training in
Toronto in March. She leapt over a snow bank and on landing broke her
right leg just above the ankle. She was admitted to Sunnybrook Hospital
where her broken bones were held together with pins. She was ordered not
to train for two months until healing was complete. She has had no
menstrual cycle for years and is a strict vegan.
Laboratory work on admission to the hospital:
Plasma oestrogen 75 pmol/L (84-1325)
Serum calcium 2.2 mmol/L (2.1-2.6)
Blood haemoglobin 120 g/L (120-155)
What is the most likely reason for her apparently fragile bones?
a) Early menopause.
b) Pregnancy.
c) “Female triad”.
d) Overtraining.
C the female triad RED-S. Vegan, menstrual problems, distance training.
9.2 2. 65-year-old woman has Crohn’s disease. This was well controlled by prednisone for several years. Lately she has had severe back pain. Radiological examination showed compression fracture of the 4 th lumbar vertebra. Laboratory test results: Serum calcium 1.75 mmol/L (2.2-2.6) Serum phosphate 0.8 mmol/L (0.8-1.4) Serum albumin 26 g/L (36-47) Serum protein 50 g/L (63-83) What diagnosis is most likely? a) Osteoporosis. b) Osteomalacia. c) Chronic malnutrition. d) Hypoparathyroidism.
A, B and C. Best as a negative- what diagnosis is not likely.
9.2 3. 50-year-old man has increasing tiredness and muscle fatigue. He also complains of thirst and polyuria. Laboratory test results on serum: Sodium 149 mmol/L (135-147) Potassium 3.5 mmol/L (3.5-5.0) Chloride 109 mmol/L (96-108) Bicarbonate 20 mmol/L (22-30) Creatinine 160 umol/L (50-120) Urea 7.5 mmol/L (3-7) Calcium 3.3 mmol/L (2.2-2.6) Phosphate 0.5 mmol/L (0.8-1.5) Albumin 35 g/L (35-50) What of the following is the most likely diagnosis? a) Kidney failure. b) Potassium deficiency. c) Hyperparathyroidism. d) Vitamin D excess.
What else should be measured to confirm the diagnosis?
a) Vitamin D.
b) Liver function tests.
c) Parathyroid hormone.
d) Calcitonin.
C and C data is from a parathyroid cancer
9.2 4. A man has chronic diarrhoea, which has led to malabsorption
syndrome. He has tingling in his hands and feet. There have been episodes
that seem like tetany. He was given vitamin D and calcium diet
supplements.
Laboratory results:
Serum calcium 1.2 mmol/L (2.2-2.6)
Serum phosphate 1.1 mmol/L (0.8-1.5)
Serum magnesium 0.25 mmol/L (0.7-1.1)
Serum albumin 40 g/L (35-50)
Serum alkaline phosphatase ALP 120 U/L (30-90)
He did not respond to therapy with vitamin D.
What do you think his serum parathyroid hormone level should be?
a) Decreased.
b) Normal.
c) Increased.
d) Variable.
A need Mg for PTH
9.2 5. 75-year-old complains of pain in his right thigh and upper arm. This
has been going on for 6 months or so and is becoming worse. He also has
become deafer than he used to be. (VIII cranial nerve). He is a retired farmer. He does not drink or smoke. He is on no medication. His right leg is
bowed laterally and his left humerus appears enlarged and warm.
Laboratory test results:
Blood haemoglobin 131 g/L (135-175)
Mean corpuscular volume 83 fL (80-99)
White cell counts 8.2 x 10 9 /L (3.5-11 x 10 9 /L)
Platelet counts 340 x 10 9 /L (150-440 x 10 9 /L)
Serum sodium 142 mmol/L (135-145)
Serum potassium 4.6 mmol/L (3.5-5.0)
Serum urea 4 mmol/L (3-7)
Serum creatinine 102 umol/L (70-120)
Serum calcium 2.23 mmol/L (2.12-2.65)
Serum phosphate 1.3 mmol/L (0.8-1.45)
Serum bilirubin 14 umol/L (3-17)
Serum alanine amino transferase ALT 25 IU/L (5-35)
Serum alkaline phosphatase ALP 584 IU/L (30-300)
What is the most likely diagnosis?
a) Osteomalacia.
b) Hyperparathyroidism.
c) Paget’s disease.
d) Osteoporosis.
C Paget’s.
9.2 6. 60-year-old man in good health complains of low back pain. He has
noticed a significant loss of weight in the last few months. He is taking
pain-killing drugs. He looks pale.
Laboratory test results:
Blood haemoglobin 90 g/L (135-170)
Platelet counts 60 x 10 9 /L (150-400 x 10 9 /L)
Erythrocyte sedimentation rate ESR 110 mm/h (0-20)
Serum protein 100 g/L (60-80)
Serum protein electrophoresis – monoclonal peak in the gamma region
Serum immunotyping showed IgG kappa chain.
Dipstick urinalysis shows some protein in his urine.
Quantitative urine protein analysis shows a great deal of protein in his
urine.
What is the most likely diagnosis?
a) Monoclonal gammopathy of undetermined significance (MGUS).
b) Bone cancer.
c) Myeloma.
d) Amyloidosis.
Why are the urine protein results different? Check all that apply.
a) The dipstick reacts with albumin only.
b) The quantitative urine protein method measures all protein.
c) There are immunoglobulin fragments in the urine.
d) The dipstick gives false negative results when there are large amounts of
protein present in the urine.
C Myeloma and dipstick A, B, C
9.2 7. Ruth Arthur: 33-year-old woman complains of morning stiffness,
painful and symmetrical swollen joints. There are several subcutaneous
nodules over the proximal extensor aspects of both forearms. She
complains of progressively worsening fatigue and lack of energy.
Laboratory results:
Blood haemoglobin 84 g/L (117-157)
Mean corpuscular volume 87 fL (80.5-99.7)
White cell counts 7.2 x 10 9 /L (3.5-11.0 x 10 9 /L)
Platelets count 438 x 10 9 /L (150-440 x 10 9 /L)
Erythrocyte sedimentation rate 46 mm/h (< 10)
Serum creatinine 84 umol/L (70-120)
Plasma glucose 4.6 mmol/L (4.0-6.0)
Serum rheumatoid factor (RF): positive (negative)
Urinalysis: no protein blood or glucose (negative)
When pregnant her symptoms lessened significantly.
What is her most likely disease?
a) Systemic sclerosis.
b) Sjogren’s syndrome.
c) Scleroderma.
d) Rheumatoid arthritis.
D rheumatoid arthritis
9.2 8. Rose Lupin, a 20-year-old woman, complains of intermittent pain and
swelling in the joints of her hands and feet. Her face is red, especially on
her cheeks below her eyes.
She does not smoke or drink, has no diarrhoea, abdominal pain or
jaundice.
Laboratory tests were ordered, abnormal results were:
Anti-nuclear antibody ANA
The diagnosis of systemic lupus erythematosus (SLE) was made.
She was put on steroids.
Two years later her ankles and abdomen start swelling. She is retaining
fluid. Her joints are normal.
Laboratory results (abnormal results only are given below):
Erythrocyte sedimentation rate ESR 100 mm/h (1 – 20)
Serum albumin 20 g/L (35 - 50)
Serum protein 35 g/L (60 - 80)
Serum creatinine 130 umol/L (40 - 130)
Serum cholesterol 7.2 mmol/L (3.9 - 6.2)
Serum complement C 3 0.4 g/L (0.5 - 1.2), C 4 0.06 g/L (0.1 - 0.5)
Serum CH 50 <30 umol/L (60 -160)
Urinalysis: protein 4+/large amount (0)
Numerous RBC and WBC granular and hyaline casts (0)
Urine protein 7 g/d (< 150 mg/d)
Serum ANA 1: 2500 (negative)
Serum Anti DNA positive (negative)
Serum rheumatoid factor negative (negative)
Serum anticardiolipin-IgG 24 GLP units (0 -20).
Which of the following is the marker for inflammation?
a) Serum anti cardiolipin.
b) Serum creatinine.
c) Erythrocyte sedimentation rate.
d) Serum albumin.
C ESR
9.2 9. Nero Wolf, 55-year-old, an obese and red-faced man, complains of
pain, redness and swelling of the metatarsophalangeal joint of the big toe.
He has had similar episodes during the last year. He has a slight fever.
Tophi are noticed on his outer ear. He is taking hydrochlorothiazide for
high blood pressure. His pulse is 90 beats/minute, blood pressure is
170/100 mm Hg and his temperature is 38 o C.
Laboratory results:
White blood cell count 12.5 x 10 9 /L (4-11 x 10 9 /L)
Band forms 2% (0-10)
Erythrocyte sedimentation rate 50 mm/h (<10)
Serum uric acid 540 umol/L (250-476)
Serum creatinine 88 umol/L (71-115)
Serum alanine amino transferase ALT 25 U/L (3-35)
Serum alkaline phosphatase ALP 60 U/L (10-100)
Serum rheumatoid factor (RF): negative (negative)
Urinalysis: no blood or protein (negative).
X-ray of right foot showed soft tissue swelling around the first MTP joint
but no erosions.
What disease is most likely to be present?
a) Pseudogout.
b) Infective arthritis.
c) Gout.
d) Lyme disease.
C gout
9.2 10. Hans Reiter, a 30-year-old man, complains of increasing right knee
pain with swelling. This started 3 days ago. Two weeks ago he had fever
and diarrhoea with blood and mucous in the faeces. This cleared up after 4
days. A week ago he had a clear penile discharge. Soon after this there
were shallow ulcers on his penis. At about this time there was bilateral
redness and itching of his eyes with a clear discharge. This has now
abated. There are hyperkeratotic nodules on the soles of feet bilaterally.
Laboratory results:
Blood haemoglobin 140 g/L (133-177)
Mean corpuscular volume 87 fL (80-99)
White cell counts 14 x 10 9 /L (3.9-10.6 x 10 9 /L)
Platelets count 345 x 10 9 /L (150-440 x 10 9 /L)
Erythrocyte sedimentation rate 84 mm/hour (< 10 mm/hour)
Serum creatinine 94 umol/L (70-120)
Urinalysis: no protein, blood or glucose (negative)
Blood cultures negative (negative)
X ray of the knee showed soft tissue swelling around the joint.
What is the most likely diagnosis of his disease?
a) Rubella infection.
b) Reactive arthritis.
c) Septic arthritis.
d) Rheumatic fever.
B Reactive arthritis
9.2 11. In 1984 Pope John Paul gave a mass at Downsview Airport, Toronto.
1,608 Police came to manage the crowd. They were all fed sandwiches.
About 400 became infected with an intestinal disease. 27 (6.5%) got
reactive arthritis. 9 recovered in 4 months but 5 years later 18 still had
arthritis.
What is the most likely cause of the illness of the chronically arthritic policemen?
a) Borrelia burgdorferi.
b) Neisseria gonorrhea.
c) Salmonella.
d) Rubella.
C
9.2 12. Vixen Fox, 55-year-old woman, complains of painful fingers and
toes. This has been endured for many years but has become worse
recently. When she goes out in the cold her fingers turn blue and then turn
red, numb and painful. Recently she has noticed a discharge of a chalky
white material from the tip of her left forefinger. For many years she has
had heart burn. Now she has difficulty swallowing unless she sits upright.
She gets breathless climbing hills or stairs, but she is not breathless lying
flat.
On examination there is a small ulcer on the left forefinger discharging
white material. There is furrowing of the skin around her mouth and her
mouth appears small. There is telangiectasia on her face. Her pulse is
76/minute and blood pressure 130/85 mm Hg.
Laboratory results:
Blood haemoglobin 122 g/L (117-157)
White cell counts 6.2 x 10 9 /L (3.5-11.0 x 10 9 /L)
Platelets count 178 x 10 9 /L (150-440 x 10 9 /L)
Erythrocyte sedimentation rate 8 mm/h (< 10)
Serum creatinine 113 umol/L (70-120)
Urinalysis: no protein or blood (negative)
What is the diagnosis of the most likely disease?
a) Scleroderma.
b) Dermatomyositis.
c) Mixed connective tissue disease.
d) Ankylosing spondylitis.
What further test would most likely confirm your diagnosis?
a) anti Jo-1.
b) Anti RNP
c) Anti Sm.
d) Anti Scl-70.
A and D
Sometimes an area of skin over his temples became hypersensitive to
touch. The onset of this disease was sudden. He complains of fatigue.
Height 167 cm, weight 60 kg, pulse is 55 beats/minute and blood pressure
is 110/70 mm Hg (normal).
Laboratory results:
Blood haemoglobin 130 g/L (130-180)
Haematocrit 0.40 (0.39-0.54)
Red cell counts 4.5 x 10 12 /L (4-6 x 10 12 /L)
White cell counts 7.7 x 10 9 /L (4-11 x 10 9 /L)
Serum creatinine 58 umol/L (44-106)
Serum calcium 2.31 mmol/L (2.2-2.6)
Serum phosphate 1.24 mmol/L (0.81-1.52)
Serum magnesium 0.88 mmol/L (0.7-1.05)
Serum albumin 40 g/L (35-50)
Serum alanine amino transferase ALT 16 U/L (<40)
Serum alkaline phosphatase ALP 104 U/L (40-120)
Serum creatine kinase CK 102 U/L (<195)
Serum C reactive protein CRP 68 g/L (<5)
Erythrocyte sedimentation rate ESR 37 mm/h (< 20)
Urinalysis negative (negative)
What is the most likely diagnosis of his disease?
a) Polymyositis.
b) Dermatomyositis.
c) Polymyalgia rheumatica.
d) Polyarteritis nodosa.
C
9.2 14. 66-year-old woman of Caribbean descent complains of 6-month
history of a pruritic rash of the scalp and chest. The rash was made worse
by exposure to sunlight. There were periorbital swelling and violaceous
papules over the dorsal aspects of the metacarpophalangeal and
interphalangeal joints. There were also poikilodermatous skin changes –
telangiectasia etc. on the upper back and anterior neck.
Laboratory results:
Serum creatine kinase 12,500 U/L (< 100)
Serum anti-nuclear antibody positive at 1:320 (negative)
Serum anti-Jo-1 present (negative)
Serum anti-Mi-2 negative (negative)
Serum anti ribonucleoprotein > 1000 units (negative)
Complete blood count, serum thyroid stimulating hormone, creatinine, liver
enzymes were within normal limits.
Skin biopsy was taken.
What is the diagnosis of the most likely disease?
a) Dermatomyositis.
b) Mixed connective tissue disease.
c) Systemic lupus erythematosus.
d) Scleroderma.
B
9.2 15. A 35-year-old father of three, a stock broker was a serious runner,
swimmer and cyclist. In 2007 he complained of intermittent back pain. X
rays showed bulging disc fusion of sacroiliac joint, distinct rounding of
vertebrae.
Laboratory test: HLA B27 positive (negative).
In 2009 he had minor left knee surgery which seemed to have activated his
immune system leading to inflamed knees, ankles, wrists, hips and ribs. He
had trouble getting out of bed. He could not straighten his left leg. The
treatment was for his to take high dose anti-inflammatory drugs. He has
become lethargic. He needs 10 hours/day sleep. He complains of
depression. He had to take leave of absence from his job.
What is the most likely disease?
a) Rheumatoid arthritis.
b) Infective arthritis.
c) Ankylosing spondylitis.
d) Septic arthritis.
C
9.3 1. 28-year-old man ran an 8 km road race in rural Australia. The
temperature was over 31 o C with 40% humidity. The race was delayed
because of the heat. The runner collapsed at 7.4 km and was taken to the
local Hospital. He was acidotic and hot. IV fluid was given with ice placed
over the major arteries. Later cool IV fluid was given. He remained hot.
Over the next few days his kidneys shut down. He continued to be acidotic
and had a temperature of 40 o C. After 12 days of treatment he was
transferred to a teaching Hospital in Sydney where he remained for most of
the next year.
Changes in serum calcium, phosphate and creatine kinase happened. His
serum CK increased to 20,000 IU/L (0-100). His liver and kidney failed. His
major muscles were swollen for days and had a tawny colour on biopsy.
This is a case of heat stroke giving rise to rhabdomyolysis.
He survived but with significant permanent muscle and nerve damage.
Early on in his disease (the first few hours) which of the following are most likely
to be decreased?
a) Calcium.
b) Phosphate.
c) Sodium.
d) Chloride
A
9.3 2. 32-year-old woman complains of episodes of blurring of vision and
muscular weakness.
Laboratory results:
Cerebrospinal fluid (CSF) protein increased.
What test should be done to confirm the diagnosis of her most likely disease?
a) Blood lead.
b) Serum antinuclear antibody.
c) CSF oligoclonal banding on electrophoresis.
d) Serum thyroid stimulating hormone. Source: colleague.
C
9.3 3. 40-year-old woman complains of generalized weakness. She can
hardly hold her head up, especially in the evenings. She has difficulty
finishing a meal because she finds it hard to chew her food. Her husband
told her that her voice has become quieter. She has lost 3 kg of weight in
the last 6 months. Her muscles seem normal but get weaker with repetitive
motion.
Which of the following tests should be done to confirm the most likely diagnosis?
a) Serum thyroid stimulating hormone.
b) Plasma serotonin.
c) Serum anti myelin sheath antibodies.
d) Serum anti-acetyl choline receptor antibodies.
D
