Approach Considerations
A thorough review of systems (ROS) and a review of medical history and medications should direct subsequent workup to assess for potential systemic causes.
Examination of all 20 nails is recommended. Close inspection of the nail plate, lunula, and proximal, distal, and lateral nail folds is essential. The clinician should make note of any periungual scale, erythema, or other cutaneous findings that might indicate an underlying primary dermatologic disorder. The presence of increased longitudinal or transverse nail curvature and onycholysis should be assessed. Nailfold capillaroscopy should be performed to look for irregularities in the capillaries of the proximal nail folds, which may indicate an autoimmune connective-tissue disorder. Signs of cyanosis or ischemia suggest that circulatory insufficiency may play a role in the nail abnormalities.
Laboratory Studies
Depending on the clinical severity and pertinent positives on ROS, it may be important to collect bloodwork to investigate further. In a brittle nail workup, physicians may be inclined to order thyroid studies, an erythrocyte sedimentation rate (marker of acute inflammation), complete blood cell counts, a comprehensive metabolic panel (which includes glucose, electrolytes, and markers of renal and hepatic function), antinuclear antibody titers, and iron (iron deficiency), ferritin, and zinc levels. If onychomycosis is suspected, nail plate and subungual debris samples should be sent for fungal culture, periodic acid-Schiff staining, and/or molecular testing.
Histologic Findings
The histopathology for onychorrhexis can be variable depending on the underlying cause. Nail plate thinning seen in onychorrhexis is caused by a shortening of the nail matrix length. However, a biopsy is not always performed, as onychorrhexis is more often a clinical diagnosis. When onychorrhexis is associated with a dermatologic disorder, biopsy of the nail matrix reveals typical histology for that disorder (eg, lichen planus, sarcoidosis, amyloidosis). In one study, [23] nail bed biopsy of age-related onychorrhexis revealed lichen planus–like changes including hyperkeratosis, hypergranulosis, and hydropic degeneration of the basal cell layer with necrotic keratinocytes. Epidermal thickening, papillomatous change, and bending of rete ridges was also noted.
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Brittle nail syndrome: Significant longitudinal ridging of the L1 and R1 fingernails in an otherwise healthy 77-year-old woman, consistent with onychorrhexis stage 3 ridging per grading criteria proposed by van de Kerkhof and colleagues. Courtesy of Amanda E Zubek, MD, PhD, FAAD.
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Brittle nail syndrome: Horizontal splitting of the free margin of the nail consistent with lamellar onychoschizia. Courtesy of Springer Healthcare (Dermatology and Therapy, 20 Nov 2019).
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Brittle nail syndrome: Moderate-to-significant longitudinal ridging of the R2-R5 fingernails in an otherwise healthy 77-year-old woman. Courtesy of Amanda E Zubek, MD, PhD, FAAD.
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Brittle nail syndrome: A 75-year-old woman with a history of hypothyroidism with moderate-to-severe longitudinal ridging of the L2-L4 fingernails consistent with onychorrhexis. Courtesy of Amanda E Zubek, MD, PhD, FAAD.
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Brittle nail syndrome: A 75-year-old woman with a history of hypothyroidism with moderate-to-severe longitudinal ridging of the R2-R4 fingernails, consistent with onychorrhexis. Courtesy of Amanda E Zubek, MD, PhD, FAAD.
Tables
Lamellar splitting defined as onychoschizia |
0 = None, clear of clinical signs of lamellar nail splitting |
1 = Mild, distal furrows, parallel to the back surface, not involving the entire free edge of the nail plate |
2 = Moderate, distal parallel furrows of the superficial nail plate involving the complete free edge of the nail plate |
3 = Severe, distal lamellar splitting of the complete free edge of the nail plate, lamellar splits covering at least one third of the nail plate |
Horizontal nail splitting from the free edge of the nail plate |
0 = None, clear of clinical signs from the free edge of the nail plate |
1 = Mild, one superficial horizontal split of the distal nail plate |
2 = Moderate, 2-3 horizontal splits of the distal nail plate |
3 = Severe, multiple horizontal splits leading to loosening of at least one third of the distal nail plate |
Assessment of ridges and longitudinal grooves |
0 = None, clear of any signs of ridging and longitudinal grooves |
1 = Mild, few plane ridges and longitudinal grooves |
2 = Moderate, few deep ridges and longitudinal grooves |
3 = Severe, more than 70% of the nail plate showing deep ridges and corresponding grooves |
Longitudinal splitting as derived from the nail matrix and defined as onychorrhexis |
0 = None, clear of clinical signs of longitudinal nail splitting |
1 = Mild, one single, superficial longitudinal split of the nail plate |
2 = Moderate, at least one deep longitudinal split of the entire nail plate |
3 = Severe, multiple, superficial and deep longitudinal splits of the nail plate |
