Renal function in psoriasis patients

ARTICLE

ejd.2011.1274

Auteur(s) : Nicoletta CASSANO¹, Michela VESTITA¹, Maria PANARO¹, Monica CARBONARA², Gino A VENA¹ g.vena@dermatologia.uniba.it

¹ 2nd Dermatology Clinic, Department of Internal Medicine, Immunology and Infectious Diseases, University of Bari, Piazza Giulio Cesare, 11, Bari, I-70124, Italy

² Italian Statistical Institute, Regional Office of Bari, Bari, Italy

The association of psoriasis with multiple diseases, especially cardiovascular and metabolic disturbances, is now established, whereas any possible link with renal disorders is not well known [1]. Renal disturbances are not traditionally included among psoriasis-related comorbidities, with the exceptions of renal amyloidosis, which is considered as a possible, albeit rare, complication of psoriatic arthritis, and renal alterations resulting from the nephrotoxic effect of drugs used to treat psoriatic disease. The existence of a specific psoriatic nephropathy has, however, been hypothesized, based on the observation of psoriasis patients with chronic glomerulonephritides [2, 3]. In a small series of children, minimal nephrotic syndrome changes were shown to precede or occur simultaneously with psoriasis, suggesting a common underlying pathogenic mechanism [4]. Finally, there is evidence of an increased urinary albumin excretion (UAE) in psoriasis patients, supporting the presence of subclinical renal involvement, since microalbuminuria is a marker of early glomerular dysfunction [5].

Our retrospective analysis involved 109 psoriasis patients and 178 age- and sex-matched controls, and was aimed at investigating subclinical renal abnormalities, as measured by creatinine clearance, estimated using the “Cockroft-Gault” formula [6], UAE and serum creatinine. Statistical analysis was performed using the two-sample Kolmogorov-Smirnov test.

Enrolled patients presented with plaque-type psoriasis of variable severity (mean Psoriasis Area and Severity Index, 16.3; range, 1.8-36.7), without psoriatic arthritis, and were all naïve to systemic anti-psoriasis therapy. Controls consisted of otherwise healthy subjects who underwent surgical excision of skin lesions. For both groups, exclusion criteria were: history of renal insufficiency or baseline serum creatinine > 1.5 mg/dL; conditions capable of influencing creatinine synthesis or potentially leading to renal dysfunction, including blood hypertension, diabetes mellitus, or administration of nephrotoxic drugs. Moreover, subjects on vegetarian, hyperproteic or other types of unbalanced diet regimens were excluded.

The results obtained are summarized in table 1 table 1. No significant differences in creatinine clearance were detected between patients and controls, while there was a trend towards higher mean UAE values in psoriasis patients, although the differences did not reach the statistical significance. On the other hand, the average creatinine serum level in psoriasis patients was significantly higher than in controls (p = 0.033).

Table 1 Renal function parameters in psoriasis patients and controls.

Results are presented as mean value and range.

^* Patients vs. controls: p = 0.033.

^§ Patients vs. controls: p > 0.05

Serum creatinine, an endogenous filtration marker almost completely filtered out by glomeruli and derived from the muscular metabolism of creatine and phosphocreatine, is the most frequently used method to assess renal function. Renal impairment, both acute and chronic, eventually leads to a rise in creatinine levels, although in chronic renal disease this increase is slower and less pronounced than expected, because tubular and intestinal creatinine secretion compensates the reduced glomerular function. To the best of our knowledge, there are presently no data concerning serum creatinine in psoriasis patients who are not burdened by comorbidities affecting the kidneys and who are naïve to potentially nephrotoxic drugs. Our results show that, within the normal range of serum concentrations, psoriasis patients had significantly higher average creatinine levels as compared to controls. It is not known whether this finding might have a true clinical relevance and/or can be due to extra-renal factors. However, in our analysis, any conditions able to affect creatinine serum levels were ruled out in both patients and controls. Higher UAE levels were also noted in psoriasis patients, in accordance with previous observations [5], although in our study the comparison with controls did not disclose statistically significant differences. Further studies in large patient populations are needed to assess the existence of psoriatic nephropathy and to estimate the risk of developing glomerular dysfunction in patients with psoriatic disease.

Disclosure

Financial support: none. Conflict of interest: none.

References

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