Nail finding	Etiologies
Beau lines (Figure 9)	Severe illness, Reynaud disease, pemphigus, chemotherapy, high fever1
Clubbing (Figure 10)	Unilateral: hemiplegia, vascular disorders
	Bilateral: empyema, cystic fibrosis, pulmonary fibrosis, celiac sprue, bronchiectasis, cardiac disease, cirrhosis, chronic obstructive pulmonary disease, inflammatory bowel disease1
Koilonychia (spoon nail; Figure 11)	Iron deficiency with or without anemia, hemochromatosis, trauma, Raynaud disease, hypothyroidism, systemic lupus erythematosus, occupational exposure to petroleum-based solvents, nail-patella syndrome10
Mees lines	Arsenic poisoning,1 other heavy metal poisoning, renal failure11
Muehrcke lines (Figure 12)	Hypoalbuminemia, nephrotic syndrome, liver disease, malnutrition12
Pincer nail (Figure 13)	Systemic lupus erythematosus, psoriasis, onychomycosis, tumors of the nail apparatus, Kawasaki disease, malignancy, beta-blocker use13,14
Splinter hemorrhage (Figure 14)	Endocarditis; psoriasis; renal, pulmonary, endocrine diseases; systemic skin conditions15