Transverse leukonychia in severe hypocalcemia

ARTICLE

Auteur(s) : Caterina FOTI¹, Nicoletta CASSANO², Vincenzo O. PALMIERI³, Piero PORTINCASA³, Anna CONSERVA¹, Michele LAMURAGLIA³, Giuseppe PALASCIANO³, Gino A. VENA¹

¹ Unit of Dermatology, Department of Internal Medicine, Immunology and Infectious Diseases, University of Bari, Piazza Giulio Cesare 11, 70124 Bari, Italy
² Istituto Dermopatico dell'Immacolata, I.D.I., I.R.C.C.S., 00167, Rome, Italy
³ Section of Internal Medicine, Department of Internal Medicine and Public Medicine, University of Bari, Piazza Giulio Cesare 11, 70124 Bari, Italy

Article accepted on 2/10/2003

Case report

A 26-year-old man developed in summer 2002 acral tetany and muscular cramps. In December 2002, laboratory examinations showed low serum calcium levels (3.8 mg/dL; normal range 8-10.3 mg/dL), and low plasma levels of parathyroid hormone (PTH) (8.2 pg/mL; normal range 10-73 pg/mL). For this reason, he started a therapy with calcium lactogluconate, calcium carbonate and calcitriol. In February 2003 he presented to our clinic with transverse leukonychia on all the fingernails. The patient reported that this had appeared in August 2002 in association with muscle cramps; he complained of mild paresthesias and carpal spasms. Chvostek's and Trousseau's signs were both positive. Investigations revealed normal haemoglobin, leukocyte count, blood glucose, urea, serum creatinine, electrolytes, albumin, magnesium, liver and thyroid function tests. Laboratory evaluation was significant for calcium (6.2 mg/dL), phosphoremia (5.0 mg/dL; normal range 2.5-4.9 mg/dL), and PTH (< 10pg/ml). Ionized calcium levels were 2.6 mg/dL (normal range 4.6-5.3 mg/dL), and calciuria was 11 mg/24h (normal range 42-352 mg/24 h). The erythrocyte sedimentation rate was 21 mm/h (normal range 0-10 mm/h); anti-nuclear, liver, kidney, microsomal, and smooth muscle autoantibodies were negative. IgA anti- tissue transglutaminase were 18.2 UA/mL (normal value < 7), IgG anti-tissue transglutaminase were 27.9 UA/mL (normal value < 30) and IgA anti-endomysium were positive. Chest radiograph, electrocardiogram, echocardiogram and ultrasound examination of thyroid and abdomen were unremarkable. Bone radiographs were normal and revealed no fracture lines. Bone mineral density, measured by dual-energy x-ray absorptiometry, was normal. The diagnosis of hypoparathyroidism was made, whereas malabsorption was suspected but not clearly confirmed.
On physical examination, multiple transverse white bands on the fingernails were observed (Fig. 1). The white lines extended across the entire width of the nail and presented a rounded edge; they did not disappear on pressure. The nail plate curvature, cuticles and lunulae were normal; there were neither signs of onychodystrophy or periungual lesions. The toenails and hairs were normal. Repeated nail scrapings did not demonstrate fungal infection and capillaroscopic examination was normal. Diagnosis of transverse leukonychia associated with hypoparathyroidism was made and the continuation of treatment with calcium supplementation and calcitriol was recommended.
After three months, calcium levels improved (7.6 mg/dl) but were still below the normal range, whereas muscular cramps and transverse leukonychia disappeared. The patient did not report any gastrointestinal symptoms. The measurement of transglutaminase antibodies was repeated, with the following results: IgA 20.8 UA/mL e IgG 53.1 UA/mL. Gastrointestinal endoscopy and intestinalbiopsy confirmed celiac disease, so that a gluten-free diet was added. After one month the calcium levels raised (9.8 mg/dL) as well as PTH values (68 pg/mL).

Discussion

Transverse leukonychia is characterized by single or multiple homogeneous, complete transverse white lines found on one or more nail plates [1, 2], which can be traumatic, toxic, infectious or due to pharmacological damage [3-6]. It can be also associated with systemic diseases [5]. The term “Mees' lines” refers to transverse leukonychia observed in arsenic intoxication, while transverse leukonychia should be used in all other cases [1]. In Mees' lines and in transverse leukonychia the damage results from abnormal keratinization of the nail plate due to transient injury to the nail matrix [4, 5, 7-9], but in Mees' lines it is also the result of the deposition of arsenic in the nail plate [10].

Hypocalcemia may be associated with nail alterations [11]. Simpson, in 1954, described various types of nail changes in association with low calcium levels [12]. It has been hypothesized that hypocalcemia can cause nail abnormalities through spasm of the arterioles of the fingertips [13]. Moreover, it has been shown that calcium plays an important role in the synthesis of hard keratins [14] and modulates the expression of α₂β₁- and α₃β₁-integrins in the nail plate [15].

To our knowledge, this is the first report of transverse leukonychia associated with hypocalcemia. The causal role of low calcium levels in our patient was clearly demonstrated by the disappearance of nail changes after calcium supplementation, which resulted in increased calcium levels, even if they remained lower than normal range, probably due to the concomitant presence of celiac disease.

In our opinion, the mechanisms responsible for hypocalcemia-induced leukonychia are represented by angiospasm and disorganization of keratin, with formation of empty spaces and consequent transverse bands of reflectance [8].
This case report underlines also the possible association of transverse leukonychia with severe systemic diseases. n

References

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