Right Test Right Time

It is often difficult to know which pathology test is needed and the burden of checking results is high.  

Dr Philip Taylor is clinical lead for pathology in Camden and is involved in an STP Right Test Right Time group, composed of GPs, clinical scientists and consultants.

We have also introduced electronic ordering for all the labs we use in Camden via tQuest to improve quality.

Coming soon: a collection of order sets via tQuest for a variety of clinical scenarios.

Philip has highlighted the key messages below, please email him if you have any suggestions or comments.

Inflammatory Markers

  • ESR should not be measured routinely
  • CRP is the preferred biomarker of inflammation: its concentration rises earlier and changes more acutely than ESR
  • The exceptions to this are to aid in diagnosis and monitoring of certain chronic conditions incuding temporal arthritis, PMR, multiple myeloma, systemic vasculitis and rheumatoid arthritis
  • Measuring ESR and CRP at the same time is not easy to justify in primary care

ESR has been removed from the front page of the tQuest order forms but can still be found by searching the text field.

Vitamin D

DO test:

  • Patients with bone disease (e.g. osteomalacia or osteoporosis) that may be improved with Vitamin D treatment
  • Patients about to start treatment with bisphosphonates, SERMs, calcitonin or denosumab.
  • Patients with musculoskeletal symptoms (generalised bone or muscle pain, proximal myopathy) that may be attributable to vitamin D deficiency.

DO NOT test:

  • Asymptomatic high risk individuals (reduced sunlight exposure, black or ethnic minority with darker skin, adults in residential care, taking medications that affect vitamin D metabolism e.g. phenobarbital, carbamazepine, phenytoin, valproate or suspected malabsortption states e.g. IBD, coeliac disease, cystic fibrosis, previous gastric bypass surgery)
  • Patients with non-specific symptoms such as fatigue, malaise, exhaustion, frailty and dizziness.

If giving Vitamin D supplements:

  • Routine monitoring of vitamin D levels is not required. 
  • Check serum calcium levels within 1 month of completing the loading regimen, in case primary hyperparathyroidism has been unmasked. 
  • Re-check Vitamin D levels 6 months after supplementation only if there is a risk of malabsorption as the cause of the deficiency.

Parathyroid Hormone (PTH)

The appropriate indications for testing PTH in primary care are:

  • Hypercalcaemia (PTH high > refer to endocrinology, PTH low > investigate for malignancy).
  • Hypocalcaemia and normal vitamin D
  • CKD Stage 4 and 5 – PTH / calcium / vitamin D should be closely monitored. These patients are likely to be seen in the low clearance clinic. Duplicate tests should be avoided.

Test calcium and not PTH after vitamin D replacement. Only test PTH if calcium level is abnormal.