As the possible causes of Muehrcke’s nails grow, a complete and detailed history is important to elicit an etiology. Questions about patients’ underlying medical conditions, exposures, medication, and occupation should be included. The chronology of nail findings in relation to history should be understood. A review of systems should also be probed, although this condition is typically benign.[9] However, treatment with systemic anticancer drugs (particularly taxanes or EGFR inhibitors) may result in nail changes, pain, and functional impairments.[10]

On physical examination, the transverse white bands run parallel to the lunula and are separated by areas of normal pink nailbed color. These white bands are only different in color and have no other palpable difference compared to the rest of the nail. Muehrcke’s nails are often present on the second, third, and fourth fingernails, whereas the thumbnail is rarely involved. The white lines disappear with pressure (hence the term ‘apparent’ leukonychia).[1] Associated melanonychia may also be present in patients undergoing chemotherapy.[11]

The history and physical examination provide the backbone for the diagnosis of this condition. Since this condition represents underlying pathophysiology involving the nail bed's vasculature, a biopsy is not recommended. Laboratory tests should be obtained as guided by patient history. Even though the number of possible etiologies continues to grow, the most important and commonly obtained test is likely serum albumin levels (levels <2.2 g/100 mL are most often associated). Other measures assessing for malnutrition could be considered, including total serum protein, serum chemistries, complete blood count, and urinalysis. For patients undergoing chemotherapy, blood levels of the therapeutic agent used can be obtained to assess for toxicity. Imaging studies are not needed.

Treatment is case-specific. In cases of Muehrcke's nails secondary to hypoalbuminemia, treatment with serum albumin infusions can result in a resolution. Treatment should be given until levels are in the normal range. However, it is important to note that treating the underlying conditions that may be the etiology aids in correcting the normal albumin levels. Some reports have shown effective fading of these lines by adding cortisone and/or corticotropin therapy to albumin infusions.[1]

The most pertinent clinical conditions on the differential diagnosis for Muehrcke's nails are Beau's lines, Mees' lines, and Terry's nails. Beau's lines are perceptible and palpable deep grooved ridges running side-to-side on the fingernail or toenail secondary to a temporary delay in nail division in the nail matrix (e.g., infection, trauma).[12] Mees' lines (also known as Aldrich or Reynolds' lines) are white, non-blanching (an important distinguishing feature from Muehrcke's nails), transverse bands running parallel to the lunula secondary to an insult to the distal nail matrix causing parakeratosis of the ventral nail plate. They are often associated with arsenic poisoning, other metal toxicity, congestive heart failure, and some infections.[13] 

In Terry's nails, most of the nail plate turns white (the lunula is obliterated) with a characteristic ground glass appearance secondary to a decrease in vascularity and an increase in connective tissue in the nail bed. They were originally associated with cirrhosis, but have now been documented in up to 25% of hospitalized patients in general.[14][15]

As a clinical finding, Muehrcke's nails themselves do not lend prognostic value. The prognosis of the patient hinges on the underlying condition that leads to this finding. As noted by Muehrcke, treatment of the underlying condition (e.g., hypoalbuminemia) can often result in the lines' disappearance.[1]

Muehrcke’s nails do not result in complications but are instead a complication of an underlying systemic condition. However, it is important to know that in the case of chemotherapy or trauma as the etiology of Muehrcke’s nails, patients may have pain and some functional limitation, which may contribute to morbidity. Patients with malignancies necessitating chemotherapy may be sick and limited functionality, so addressing functionality concerns and pain related to Muehrcke’s nails is important. Some patients may also be concerned about the cosmetic appearance of their nails. For these patients, it is important to understand the psychosocial ramifications of how this condition may bother them and form a strong partnership to address these concerns by treating the underlying condition.

Proper nutrition and receiving and adhering to treatment for underlying medical conditions may prevent Muehrcke’s nails. It is important to convey to patients a few concepts regarding this condition to prevent unnecessary anxiety. First, it is important to inform them that Muehrcke’s nails are primarily a cosmetic concern. Second, it is equally important to make them aware that this condition often improves with treatment of the underlying condition. If no underlying condition is known at the time of diagnosis, calmly explaining to patients that a workup will need to be initiated is important for them to understand that this condition is linked to an underlying disorder.

Muehrcke’s nails are cutaneous manifestations of underlying systemic disease with unclear prevalence. When a provider notices it, it is best managed by an interprofessional team of a primary care clinician, a dermatologist, and a specialist whose specialty is most pertinent to the patient’s underlying systemic condition.

A dermatologist’s involvement helps make the diagnosis, monitor progression, and insight into other hair, nail, or skin disorders, which may additionally manifest from an underlying condition. A primary care provider is important to assess the patient’s baseline health, launch medical workup, and carefully coordinate care with appropriate specialists. Specialists can help treat underlying conditions or modify treatment if the Muehrcke’s nails are a result of therapy (e.g., chemotherapy). Often, the outcomes of this condition depend on how amenable the underlying condition to treat.