Manifestations of congenital hypothyroidism is the low level of circulating thyroxine (T4).

Many clinical or laboratory parameters such as blood pressure, serum cholesterol, or blood glucose are measured using a continuous scale as opposed to dichotomous (yes/no) expression. In those situations, physicians often use predetermined cut-off levels to distinguish between individuals with and without the condition of interest. 

One of the main manifestations of congenital hypothyroidism is the low level of circulating thyroxine (T4).  Newborns with low T4 levels are sent for additional testing to determine the levels of thyroid stimulating hormone (TSH) and to repeat the T4 test. Elevated levels of TSH in combination with persistently decreased levels of T4 are considered sufficient to diagnose hypothyroidism. 

 

The results of T4 screening for 280 cases of confirmed hypothyroidism and 520 randomly selected newborns without the disease are shown below.

 

 

 

T4 level (nmol/l) Hypothyroidism (N=280) No hypothyroidism (N-520)

  < ³ < ³

120 280 0 512 8

80 140 140 120 400

60 40 240 0 520

 

 

8.  What are the sensitivities and specificities of the T4 test at different cutoffs?  Is there a pattern? 

 

60

 

  Y N  

P 40 0 40

N 240 520 760

  280 520 800

Sensitivity = 14%

 

 

 

Specificity = 100%

 

 

 

80

 

  Y N  

P 140 120 260

N 140 400 540

  280 520 800

Sensitivity = 50%

 

 

 

Specificity = 77%

 

 

 

120

 

  Y N  

P 280 512 792

N 0 8 8

  280 520 800

Sensitivity = 100%

 

 

 

Specificity = 2%

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9.  Which cutoff would you choose?  Justify your answer.

 

120 and 60 are too one-sided, so 80 is the best choice

 

 

 

LR+ = 50/23 = 2.17 = 2.1

 

LR- = 50/77 = 0.64 = 0.6

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10. You are asked to calculate the PPV of the T4 test in the general population.  What is your response?

Collepals.com Plagiarism Free Papers

Are you looking for custom essay writing service or even dissertation writing services? Just request for our write my paper service, and we'll match you with the best essay writer in your subject! With an exceptional team of professional academic experts in a wide range of subjects, we can guarantee you an unrivaled quality of custom-written papers.

Get ZERO PLAGIARISM, HUMAN WRITTEN ESSAYS

Why Hire Collepals.com writers to do your paper?

Quality- We are experienced and have access to ample research materials.

We write plagiarism Free Content

Confidential- We never share or sell your personal information to third parties.

Support-Chat with us today! We are always waiting to answer all your questions.