Re-testing Guidance for stable in-patients

Any intervention that acts to reduce waste and avoid unnecessary phlebotomy/booking appointment for the patient can only be seen as contributing to the optimisation of patient care as supported by National drivers such as 'getting it right first time' and local initiatives such as the Leeds Improvement Method.

Minimal retesting intervals (MRI) are defined as the minimum time before a test should be repeated, based on the properties of the test and the clinical situation in which it is used. Such intervals aim to reduce repeated and unnecessary pathology testing, minimize harm to patients and save valuable resources.

This guidance specifically relates to stable in-patients and is designed to guide effective use of laboratory tests. It is not intended to be prohibitive as testing should be primarily determined by the clinical scenario.

In the table below, the minimum re-test intervals are listed

Table of Minimum Re-Test Intervals in stable in-patients

 Test Name Test Interval 
 Full Blood Count (FBC) 24 Hours 
 Urea and Electrolytes (U+E) 24 Hours 
 C Reactive Protein (CRP) 48 Hours 
 Liver Function Test (LFT) 48 Hours 
 Calcium Profile / Phosphate (Ca / PO4) 48 Hours 
 Magnesium (Mg) 48 Hours 
 Erythrocyte Sedimentation Rate (ESR) 7 Days 
 Serum Vitamin B12 56 Days 
 Folate 21 Days 
 Ferritin 21 Days 
 Progesterone 7 Days 
 Prolactin 7 Days
 Oestradiol 7 Days 
 Luteinizing Hormone (LH) 7 Days 
 Follicular Stimulating Hormone (FSH) 7 Days
 Anti Neutrophil Cytoplasmic Antibodies (ANCA) 14 Days 
 Anti Nuclear Antibodies (ANA) 20 Days 
 Immunoglobulins (Ig) 28 Days 
 Glycosylated Hb / Haemoglobin A1C (HbA1C) 40 Days 
 Vitamin D 28 Days 
 Lipids           28 Days 
 Ca125 13 Days 
 Alpha-fetoprotein (AFP) 6 Days 
 Prostate Specific Antigen (PSA) 13 Days 
 Insulin Like Growth Factor (IGF-1) 14 Days 
 Autoantibody Screen 90 Days 
 Complement C3,C4 90 Days 
 Protein Electrophoresis 180 Days 


The minimum intervals listed above are adapted from the following document:National minimum retesting intervals in pathology. A final report detailing consensus recommendations for minimum retesting intervals for use in pathology. December 2015

Page updated: 28/10/2019 

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