A New Grad's Guide to Ordering Lab Work

Jul 22, 2015
9 min read

You’ve graduated, you’re killing it at your new practice, and you have a patient in your chair with a condition that needs more investigation. Maybe it’s an optic neuritis or maybe the uveitis you’ve been managing isn’t responding like you thought it would.

Regardless, you know lab work would help….so now what??? Many docs don’t feel comfortable with ordering labs and will choose to refer a patient to another optometrist or ophthalmologist who is more familiar with them, but trust me, YOU don’t have to do that!

Whether you’ve never ordered before or it’s just been awhile, this guide will give you 4 quick tips and insight into handling those patients yourself. I promise you can do it!

1. Be familiar with what you’re ordering

The biggest key to ordering labs for a patient is knowing what you are ordering.

There are many different lab orders you can and may need to make. Familiarizing yourself with the most common ones will help substantially when you have a challenging patient to manage. Be sure to include any test you think may be of benefit on your initial order. While occasionally unavoidable, it is better to order all labs you think you might find helpful to begin with, rather than have to ask the patient to go back for multiple rounds of lab work.

Here are some of the most common tests you should make sure you remember:

CBC c diff

  • Full name: complete blood count with differential
  • Description: full panel describing blood make up (erythrocyte, leukocyte, neutrophil, plasma count, etc); commonly used to evaluate for anemia and infection markers (i.e., high WBC count)
  • Fasting: no

BMP (aka Chem-8)

  • Full name: BMP = basic metabolic panel
  • Description: measures glucose, electrolytes, and kidney function; exact make up of this panel may vary between labs; useful in determining any underlying systemic problems the patient may have
  • Fasting: no


  • Full name: erythrocyte sedimentation rate
  • Description: test measuring the rate at which RBCs settle within 1 hour; inflammation marker
  • Fasting: no
  • **Should always be ordered when suspicious of giant cell arteritis**


  • Full name: C-reactive protein
  • Description: inflammation marker; protein is produced by the liver and increases with systemic inflammation
  • Fasting: no
  • **Should always be ordered when suspicious of giant cell arteritis**


  • Full name: Human leukocyte antigen B27
  • Description: presence of this antigen is indicative of the patient being at risk for or having an autoimmune disorder; the test is non-specific for which autoimmune disorder the patient may be affected by
  • Fasting: no


  • Full name: Fluorescent treponemal antibody absorption
  • Description: evaluates whether or not the patient has ever had syphilis; once the patient has been infected, this test will always be positive, even once the active infection is cleared
  • Fasting: no


  • Full name: Rapid plasma reagin
  • Description: test for active syphilis; less specific than FTA-ABS, but more indicative of an active infection
  • Fasting: no

Thyroid Panel (T4 and TSH)

  • Full name: T4 = thyroxine; TSH = thyroid stimulating hormone
  • Description: measures the amount of free T4 in the patient’s blood- indicative of overproduction of the main hormone produced by the thyroid gland (hyperthyroidism); measures the amount of TSH in the blood- indicative of lack of production of appropriate hormones by the thyroid gland, resulting in excess stimulating hormone (hypothyroidism)
  • Fasting: no
  • **Useful in patients suspicious for Grave’s disease**


  • Full name: Glycosylated or glycated hemoglobin test
  • Description: measurement of average glucose level over the last 3 months
  • Fasting: no
  • **Better indicator of overall control of diabetes than glucose measurement**


  • Full name: Antinuclear antibody
  • Description: autoimmune disorder marker; non-specific
  • Fasting: no


  • Full name: Angiotensin-converting enzyme
  • Description: elevated levels indicate likely sarcoidosis
  • Fasting: no
  • **Important test for patients with granulomatous uveitis**

Lipid Panel

  • Full name: Cholesterol or lipid panel
  • Description: measures overall cholesterol, HDL, LDL, and triglyceride levels in the patient’s blood
  • Fasting: yes (>6 hours without food is typically sufficient)
  • **Consider ordering when a patient presents with unilateral arcus, early-onset arcus, Hollenhorst plaque, or CN III palsy**

ELISA for Lyme disease

  • Full name: Enzyme-linked immunosorbent assay
  • Description: positive testing indicates that a patient is infected by Lyme disease
  • Fasting: no
  • **Should be run on patients with granulomatous uveitis who live in or have been to regions affected by Lyme disease**


  • Full name: Purified protein derivative
  • Description: skin test to evaluate for tuberculosis; if a patient has tested positive in the past, should consider a chest X-ray
  • Fasting: no
  • **Important test for patients with granulomatous uveitis**

2. Know for which ocular conditions you should order

Some conditions should trigger an automatic lab work up, while others may be dependent upon management success or severity of presentation. Below you will find a list of five common conditions which routinely warrant lab orders and the types of tests you should consider for each. Keep in mind that other problems may also benefit from a systemic work up should you find them unusual or non-responsive to treatment.

  1. Optic neuritis- any patient who presents with ONH edema and vision loss should be strongly considered for a lab work up due to the possibility of arteritis. Some clinicians will choose not to do this in patients who have systemic conditions that are likely to cause NAION (such as uncontrolled, severe diabetes) or who do not have other concurrent symptoms of arteritis, however, it is always best to be safe rather than sorry. You should include the following tests in your panel for this condition: CBC c diff and BMP to evaluate overall systemic health, CRP and ESR to look for inflammation, HLA-B27 and ANA to determine the possibility of underlying autoimmune disorders, FTA-ABS and RPR due to syphilis’ capability of masquerading, and HbA1C to make sure the patient is not an undiagnosed or uncontrolled diabetic.
  2. Papilledema- bilateral ONH edema will often prove to be pseudotumor cerebri. However, a systemic work up is necessary to make sure there is not a different underlying cause, especially if the patient has vision loss. Your lab order for this condition is similar to the one for optic neuritis. It should include: CBC c diff, BMP, CRP, ESR, HLA-B27, ANA, FTA-ABS, and RPR.
  3. Uveitis- unilateral and primary uveitis does not warrant a lab order as it is typically idiopathic. However, unresponsive or recurrent cases or those in which the condition is bilateral or granulomatous should. Granulomatous uveitis is most often caused by sarcoidosis, herpes simplex or zoster, Lyme disease, tuberculosis, or syphilis. Therefore, you should run a full panel including the tests mentioned in the last two conditions, as well as orders specific for these conditions including ACE, ELISA for Lyme, and a PPD skin test.
  4. Third nerve palsy- all CN III palsies should be considered compressive until proven otherwise. While imaging is integral for determining the presence or absence of an aneurysm or mass, lab work is still important in order to determine whether or not the patient has underlying systemic problems that may lead to ischemia. Your order should include: CBC c diff, BMP, CRP, ESR, HLA-B27, ANA, FTA-ABS, RPR, HbA1C, and a lipid panel. Remember the patient should be fasting for at least 6 hours prior to the lipid panel measurement.
  5. Graves’ disease- if you suspect a patient may have Graves’, you should order a thyroid panel. It can also be beneficial to order CBC c diff, BMP, ESR, and CRP testing to evaluate the patient’s overall systemic health and level of inflammation.

3. Find a few labs in your area that are easy to work with

Call around to your local hospitals and labs to introduce yourself and find out pertinent information you’ll need to work with them efficiently. It is helpful to find out their location to guide your patients, their protocols for orders, and how quickly they can typically get you preliminary and final results. Most labs will accept a written order on an RX pad for any tests you require. Turn around for the tests listed above is often no more than 24-48 hours for preliminary results and within 1 week for final results if you find a lab that will work well with your office.

4. Pre-printed orders can make life easier

One of the most useful changes we have made in my office is to have pre-printed blood work orders like the one below. You may not have to use them often, but having your most common tests listed on a handy RX pad can cut time and help you remember exactly what tests you do and don’t want to have performed. You can circle the ones you want or strike out the ones you don’t, and you can always free hand any additional orders you may need. Just print the patient’s name at the top, sign the bottom, and you’re good to go! I highly recommend having these around!

ordering lab work.jpg

Don’t be afraid to adapt your lab orders to meet the needs of your particular clinic or patient base.

Even if you end up having to refer a patient for the condition you are managing, having the lab work will allow you to make a more educated referral and likely speed up the treatment of your patient. ODs are more than capable of fully managing most of the problems that present in our chairs, and you can help establish yourself as a leader in your local eye care community through taking that extra step toward understanding the full clinical picture.

Lab work is your friend, not something to be unsure of, so order whenever you deem necessary! Good luck, new grad, and happy diagnosing!

If you’d like more information about these tests or other tests you may be ordering, check out the National Library of Medicine’s MedlinePlus!

If you have any questions, please do not hesitate to comment below!

About Patricia Fulmer, OD, FAAO

Dr. Fulmer is the sole owner of Legacy Vision Center, a cold start, medically focused practice in Huntsville, AL, which launched at the end of 2020. A graduate of the UAB School of Optometry, she completed an ocular disease and …

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