Data Interpretation:
Screening Tests
The following questions highlight many aspects of the section that relates to Screening Tests. Our aim is to continually update and expand this section - so keep coming back!
Question 1
A 2-year-old girl is brought to your clinic. Developmentally normal, her parents had noticed her to be bruising easily. Coagulation tests show:
| Test | Patient | Reference Range |
| PT | 13s | 11-14s |
| APTT | 105s | 23-35s |
| Fibrinogen (Clauss) | 2.7g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
A. What other questions might you ask the parents?
B. Briefly outline how you would investigate the clotting abnormalities.
Question 2
A 45-year-old man is referred for further investigation following the finding of an abnormal coagulation profile. He had contacted his GP having developed easy bruising and epistaxes. His health had previously been excellent apart from a recent chest infection for which he had been prescribed amoxicillin.
Investigations show:
| Test | Patient | Reference Range |
| PT | 45s | 11-14s |
| APTT | 79s | 23-35s |
| Fibrinogen (Clauss) | 2.9g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
A. Outline how you would investigate this patient.
B. Give the reasons behind these investigations.
Question 3
A 23-year-old woman presents to her GP with menorrhagia. The GP requests a coagulation screen and the results of this are shown below:
| Test | Patient | Reference Range |
| PT | 34s | 11-14s |
| APTT | 82s | 23-35s |
| Fibrinogen (Clauss) | 2.6g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
- What questions might you ask this lady that would be of relevance?
- How would you proceed with the investigation of this patient?
Question 4
A 45-year-old man presents with an extensive above knee DVT extending into the iliac veins. He is otherwise well with no past medical history of note.
His pre-anticoagulation screen shows:
| Test | Patient | Reference Range |
| PT | 14s | 11-14s |
| APTT | >120s | 23-35s |
| Fibrinogen (Clauss) | 3.2g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
A. What are the possible explanations for these findings?
Question 5
A 10-day-old baby, previously well, breast fed and born at home is found by his parents unconscious and bleeding from mouth and gums. The only history of note is that the mother had had a major post partum haemorrhage and had required emergency admission to hospital.
A coagulation screen shows:
| Test | Patient | Reference Range |
| PT | 102s | 11-14s |
| APTT | >120s | 23-35s |
| Fibrinogen (Clauss) | 1.9g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
A. What is the most likely explanation for these findings?
B. Why does this occur?
Question 6
The following results were found in a 32-year-old woman as part of a Well Woman Screen.
| Test | Patient | Reference Range |
| PT | 12s | 11-14s |
| APTT | 95s | 23-35s |
| Fibrinogen (Clauss) | 3.9g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
List additional tests you would perform following the findings shown above to clarify the diagnosis
Question 7
What might explain the laboratory findings shown below?
| Test | Patient | Reference Range |
| PT | 65s | 11-14s |
| APTT | 75s | 23-35s |
| Fibrinogen (Clauss) | 0.8g/L | 1.5-4.0g/L |
| Thrombin Time | 47s | 10-13s |
Question 8
A clotting screen on a woman of Iranian descent shows the following results:
| Test | Patient | Reference Range |
| PT | 35s | 11-14s |
| APTT | 56s | 23-35s |
| Fibrinogen (Clauss) | 2.8g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
A. What coagulation abnormalities might explain these findings.
B. What additional tests would you perform?
Question 9
A 56-year-old woman with a colonic carcinoma is admitted for surgery. A pre-operative clotting screen shows:
| Test | Patient | Reference Range |
| PT | 14s | 11-14s |
| APTT | 76s | 23-35s |
What other tests would you request and why?
Question 10
A 23-year-old woman develops a DVT. There is no other personal or family history of note?
| Test | Patient | Reference Range |
| PT | 14s | 11-14s |
| APTT | 95 | 23-35s |
A. Comment upon the results of the PT and APTT.
B. What tests would you request next?
Question 11
A 53-year-old man is admitted unconscious to casualty. His coagulation results are shown below:
| Test | Patient | Reference Range |
| PT | >120s | 11-14s |
| APTT | >120s | 23-35s |
| Fibrinogen (Clauss) | 2.01g/L | 1.5-4.0g/L |
| Thrombin Time | 13s | 10-13s |
A. What is the most likely explanation for these findings?
Question 12
Comment upon the following results in an 18-year-old asymptomatic individual.
| Test | Patient | Reference Range |
| PT | 45s | 11-14s |
| APTT | 46s | 23-35s |
| Fibrinogen (Clauss) | 0.8g/L | 1.5-4.0g/L |
| Thrombin Time | 45s | 10-13s |
| Reptilase Time | 51s | 11-14s |
Question 13
An 8-year-old boy is admitted with prolonged bleeding following tonsillectomy. His clotting screen shows:
| Test | Patient | Reference Range |
| PT | 25s | 11-14s |
| APTT | 64s | 23-35s |
A. What factor assays would you request and why?
Question 14
Give 7 possible explanations for the following findings
| Test | Patient | Reference Range |
| PT | 21s | 11-14s |
| APTT | 62s | 23-35s |
Nb. There are more than 7!
Question 15
A 23-year-old male is investigated for a possible bleeding disorder whilst living in Paris. He has a bleeding time performed and this is found to be significantly prolonged at 26 minutes (NR: <10 minutes).
A. Briefly outline the principles of the bleeding time.
B. What abnormalities would explain the prolonged bleeding time in this patient?
Question 16
A thrombin time is performed in a 78-year-old man with an extensive lower limb DVT prior to starting him on unfractionated heparin.
| Test | Patient | Reference Range |
| Thrombin Time | 32s | 10-13s |
A. What is your differential diagnosis?
B. What tests would you request next?
Question 17
A 56-year-old man with a long history of COPD is admitted for surgery. His pre-operative investigations show a Hb of 19g/dl and an Hct of 0.58.
His pre-operative clotting screen shows:
| Test | Patient | Reference Range |
| PT | 20 | 11-14s |
| APTT | 47 | 23-35s |
A. What do you think might explain these findings?
B. What would you do next?
Question 18
A 41-year-old male with nephrotic syndrome is admitted for renal biopsy. His pre-biopsy clotting screen shows:
| Test | Patient | Reference Range |
| PT | 13 | 11-14s |
| APTT | 36 | 23-35s |
| Thrombin Time | 19 | 10-13s |
| Reptilase Time | 23 | 11-14s |
A. Comment upon the results of these tests.
B. What advice would you give to the nephrologists regarding the renal biopsy?
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