Nail changes in chronic kidney disease: A cross-sectional study

INTRODUCTION

Chronic kidney disease (CKD) is a progressive condition that affects the kidneys’ ability to filter waste and excess fluids from the blood, leading to a wide range of systemic manifestations. While the focus of CKD management often centres on the kidneys and related cardiovascular concerns, the disease can also have notable dermatological manifestations.^[1] One of the most visible and frequently overlooked signs of CKD is the changes in the nails. These nail abnormalities can be subtle but may provide valuable clinical insights into the progression of the disease and the patient’s overall health status.^[2]

Nail changes, though not always specific to CKD, can be indicative of underlying systemic disturbances, particularly in the context of chronic renal insufficiency.^[2] Understanding the relationship between CKD and nail changes can help early detection and management.^[3] These alterations often reflect the severity of kidney dysfunction and may also serve as early indicators of complications such as anaemia, uraemia and bone mineral disorders, commonly associated with CKD. Furthermore, examining nails can provide clinicians with non-invasive diagnostic clues, aiding the assessment of disease progression and treatment response.^[4]

The clinical relevance of nail changes in CKD patients is underappreciated, yet they represent an important aspect of the disease’s systemic impact. The present study aims to explore the various types of nail changes observed in CKD patients, their potential mechanisms and their significance in the overall management of the disease. The study also aimed to observe the correlation between the severity of CKD and nail changes, if any.

MATERIAL AND METHODS

This was a cross-sectional observational study to evaluate the prevalence and correlation of nail manifestations in patients with CKD. It was approved by the institutional ethical committee vide approval number SSMC/MED/IEC-030/March-2023. It was conducted over a period of 24 months.

Patients were recruited from outpatient departments of dermatology, general medicine, nephrology, and the dialysis unit. The timeframe ensured that seasonal variability in nail presentations was accounted for. It also enabled the researchers to capture a sufficient number of cases across different stages of CKD. Adults aged 18 years or older, diagnosed with CKD irrespective of its stage or severity, and with or without diabetes or hypertension were included. CKD was graded into 5 stages according to glomerular filtration rate. We excluded patients with renal transplant, those on post-transplant dialysis, patients with concurrent liver diseases, patients with pre-existing nail conditions due to trauma, comorbidities such as cardiovascular diseases, pulmonary diseases, connective tissue disorders, endocrine disorders (hypothyroidism, hyperthyroidism) and those unwilling to participate in the study.

Purposive sampling was employed. The sample size was calculated based on the prevalence of nail changes in CKD patients as reported in prior research. Based on previous studies, using a prevalence rate of 94.3 %, a precision level of 4.5% and a 95% confidence interval, the minimum required sample size was determined to be 102 patients.^[3] Participants were stratified into subgroups based on CKD stage and comorbidities (diabetes and hypertension), to facilitate a comparative analysis of nail manifestations and their correlation with disease severity and management approach. The recorded parameters included demographic details, CKD stage, treatment modality, presence of comorbidities and specific nail findings. Laboratory parameters, such as urea, creatinine, calcium-phosphate levels and parathyroid hormone levels, were also recorded.

Each participant underwent a detailed history-taking, focusing on CKD diagnosis and nail-related complaints. A thorough dermatological examination was performed under proper lighting to assess skin, hair, nails and mucosa. Nail changes were assessed for all the digits of the upper limbs and lower limbs. Specific investigations, such as potassium hydroxide mount and biopsies, were performed when indicated. All findings were documented systematically using a structured proforma.

Data collection involved both direct clinical observations and patient-reported outcomes. Standardised forms were used to record demographic, clinical and laboratory data. Nail findings were documented photographically with patient consent. The data were double-checked for accuracy and completeness before being entered into a secure database for analysis.

The data were analysed using the Statistical Package for the Social Sciences version 22. Descriptive statistics were used to summarise demographic and clinical variables. Inferential statistics, such as Chi-square tests and Student’s t-tests, were employed to examine correlations between CKD severity and nail changes. P < 0.05 was considered statistically significant.

RESULTS

The total number of patients studied with CKD was 103. The age of the patients varied from 18 to 86 years with a mean of 49.34 years. Of these, 26.20% were in the age group between 41 and 50, 25.2% belonged to 51–60 years of age and 22.3% were <40 years of age. Out of 103 patients, 64 (62.1%) were male and 39 (37.90%) were female.

The duration of illness from the time of diagnosis ranged from 3 days to 3 years. A total of 52 (39.80%) patients reported <6-month duration of illness, followed by 35 (12.4%) patients with 6–12-month duration. Only 16 patients had more than 1-year duration (2.90%). The duration of dialysis ranged from 2 months to 3 years. It was <1 year for 58 (56.3%) patients, more than 1 year for 30 (29.1%) patients, and 15 (14.6%) patients were not on dialysis.

Of the 103 patients, 39 (37.86%) patients had diabetes and 54 (52.4%) patients were hypertensive. Blood urea ranged from 64 to 193 mg/dL with 62 (60.19%) patients having levels <100, 13 (12.62%) patients having between 101 and 150, and 28 (27.10%) patients having >150. Serum creatinine values ranged from 1.5 to 14.4 mg/dL. It was <5 mg/dL in 13 (12.6%) cases, between 5 and 10 for 86 (83.4%) patients and more than 10 mg/dL for 4 (3.88%) patients.

Only 4 (3.88%) patients had a history of smoking, whereas 10 (9.7%) patients consumed alcohol. Only 7 (6.79%) patients had a positive family history, all paternal.

Of the 103 patients, 58 (56.3%) patients showed nail changes. Fingernails were affected more frequently than toenails, with 38 patients having only fingernail changes, 10 having only toenail changes and 10 patients having both involved. The most common change was half and half nails, seen in 23 (22.3%) patients. The other changes observed were absent lunula in 16 (15.5%) patients, koilonychia in 15 (14.5%), subungual hyperkeratosis in 8 (7.7%), onycholysis in 6 (5.8%), Beau’s lines in 6 (5.8%), onychomycosis in 6 (5.8%) and melanonychia in 5 (4.8%) patients. The least common changes were Mees’ lines seen in 2 (1.9%) patients, racquet nail in 1 (0.97%) patient, clubbing in 1 (0.97%) patient, pterygium in 1 (0.97%) patient, worn down nail in 1 (0.97%), onychoschizia in 1 patient (0.97%) and Muehrcke’s lines in 1 patient (0.97%) as shown in Table 1. A total of 20 patients had two or more nail changes.

The most common changes in fingernails were half-and-half nails in 14 patients, followed by absent lunula in 13 patients, koilonychia in 11 patients, melanonychia in 4 patients, onycholysis in 3 and Beau’s lines in 2. The most common nail changes in toenails were half-and-half nails in 9 patients, followed by subungual hyperkeratosis in 7, onychomycosis in 5, koilonychia in 4 and absent lunula in 3 patients.

DISCUSSION

CKD can affect people of any age group, but it more commonly affects older adults. The present study had patients of wide age range, between 18 and 86 years, with a mean of 49.34 years. This is in accordance with the study done by AlThnaibat et al. in Jordan in 2025 in which the mean age was 48.31 years (range 11-82 years).^[5] The majority (26.2%) of our patients belonged to the age group of 41–50 years.^[5] In a study done by Adejumo et al. in 2019, the mean duration was 10.12 months.^[6] There was a male preponderance with 64 males (62.1%). In a study done in Manipur in 2020, involving 100 patients, Devi et al. had reported a mean duration of 9.85 months of CKD.^[7]

With reference to the temporal span of dialysis, an extensive body of literature underscores considerable heterogeneity, as exemplified in the seminal work of Maskey et al., wherein 80 individuals afflicted with CKD were evaluated, demonstrating a mean dialysis duration of 40.28 ± 11.09 months.^[8] This contrasts markedly with the findings of Shirzadian Kebria et al. (2023), who investigated a cohort of 150 patients exhibiting a substantially abbreviated mean dialysis interval, ranging approximately 8.7 months, thereby accentuating the prevailing divergence in observational durations across studies.^[9]

The blood urea level of patients ranged from 64 to 193 mg/dL. Of these 72 (69.9%) patients had blood urea levels of <100. It was between 101 and 150 for 3 (2.9%) patients and more than 150 for 28 (27.10%) patients.

Nail changes

In Figure 1, Half-and-half nails, also known as Lindsay’s nails, were seen in 22.3% patients [Figure 1a]. This is in accordance with the study done by Adejumo et al. in 2019 in which 45.7% of patients had Lindsay’s nails as the most common nail manifestation.^[6] These may be a result of decreased renal perfusion and vascular abnormalities involving proximal blood vessels of the nail bed leading to decreased circulation and pale appearance of the proximal half. The distal blood vessels affected later, maintain their normal colour and appearance. Half-and-half nails were seen in 73.5% of Stage 5 CKD and 6 (73.91%) patients on dialysis for more than 1 year. This shows that the condition does not improve with dialysis or the treatment of CKD. In a study done by Kabra et al., similar findings were seen, in which 12% of patients on dialysis had half-and-half nails and the condition did not improve with treatment of CKD or dialysis.^[2] Half and half nails were common in patients with blood urea in the range of 150–200 mg/dL, suggesting a possible association with elevated nitrogenous wastes, particularly blood and creatinine.

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Figure 1:

(a) A 42-year-old female with Stage 5 chronic kidney disease (CKD) on dialysis with half-and-half nail and absent lunula over the thumb nail. (b) A 46-year-old female with Stage 5 CKD on dialysis with absent lunula over thumb nail. (c) A 62-year-old male with Stage 5 CKD with subungual hyperkeratosis over the great toe nail. (d) A 56-year-old male with Stage 5 CKD with subungual hyperkeratosis over the great toe, koilonychia of the third toe and melanonychia of the fourth toe nail. (e) A 65-year-old male with Stage 5 CKD with Muehrcke’s lines of all 10 digits. (f) A 41-year-old male with Stage 5 CKD with onychomycosis of the left great toe and pterygium of the left great toe and second toe. (g) A 46-year-old male with Stage 5 CKD with racquet nails of both the thumbs. (h) A 43-year-old male with Stage 5 CKD with clubbing of all 10 digits. (i) A 23-year-old female with Stage 5 CKD with worn down nails of the fingers. (j) A 58-year-old female with Stage 5 CKD with onychoschizia of the index finger.

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Absent lunula was the second most common nail feature seen in 16 patients [Figure 1b]. In a study done by Kabra et al., in 2022, it was not a significant nail finding (4%).^[2] It may be due to the diminished blood supply to the lunula and increased uraemia, which hinders the nail matrix function. In the category of patients with absent lunula, 3 (18.75%), 5 (31.25%), 8 (50%) had urea levels <100, 100–150 and more than 150 mg/dL. With an increase in uraemia, there is an increase in the prevalence of absent lunula. However, 6 patients with absent lunula had creatinine values <5 mg/dL, 8 patients had creatinine values ranging from 5 to 10 mg/dL and 2 patients had creatinine values above 10 mg/dL. Thus, the change may not alter much with the creatinine values. In a study done by Kabra et al., an absent lunula was seen in 4% of the patients and the nail finding did not alter much with blood urea or creatinine values.^[2]

Koilonychia was the third most common nail finding seen in 15 patients with 8 patients presenting during first year of dialysis and remaining 7 with a duration of more than one year. [Figure 1d]. The most common cause of koilonychia in CKD is iron-deficiency anaemia and uraemia. Overall, 46.66% of koilonychia patients had a blood urea level of <100 mg/dL and 33.3% had a blood creatinine value of <5 mg/dL. This could reflect the multifactorial aetiology of koilonychia including iron-deficiency anaemia, a common comorbidity in early to moderate CKD. As renal function continues to decline, the relative contribution of anaemia to nail morphology may be overshadowed by other systemic effects of uraemia. This shift could explain the reduced frequency of koilonychia at higher urea concentrations, where other nail changes, like Lindsay’s nails become more prominent.

Subungual hyperkeratosis was seen in 8 (7.7%) patients. The cause of subungual hyperkeratosis has been attributed to an increased cytokine production promoting the growth of keratin under nail bed [Figure 1c]. Other nail changes commonly seen were onycholysis, Beau’s lines, onychomycosis and melanonychia. Beau’s lines in CKD patients suggest sudden arrest in nail growth due to an imbalance in calcium and phosphate levels, altering the integrity of the nail matrix. Out of six cases of onychomycosis, four were seen in diabetics [Figure 1f]. KOH mount showed multiple septate branched hyphae, suggesting tinea unguium. The least common nail changes were Mees’ lines seen in 2 (1.9%) patients, racquet nails in 1 (0.97%) patient [Figure 1g], clubbing in 1 (0.97%) patient [Figure 1h], pterygium in 1 (0.97%) patient [Figure 1f],worn down nail in 1 (0.97%) patient [Figure 1i], onychoschizia in 1 patient (0.97%) [Figure 1j] and Muehcke’s lines in 1 patient (0.97%) as shown in Figure 1e. However, compared to other studies like Kabra et al. in 2022, pitting was not seen in the present study.^[2]

CONCLUSION

By recognising these nail changes and signs early, healthcare providers can gain valuable insights into the progression of CKD and better tailor care to improve both kidney and overall health. In the world of chronic disease management, sometimes, the answers are right at our fingertips, literally.