S Zaki, N Hamed, H Elwakil, A Ketat
elderly patients, iron deficiency anaemia, n-acetyl-β-d-glucosaminidase, renal tubular function
S Zaki, N Hamed, H Elwakil, A Ketat. Study Of N-Acetyl-Β-D-Glucosaminidase In Elderly Patients With Iron Deficiency Anaemia. The Internet Journal of Hematology. 2008 Volume 5 Number 2.
Mean urinary levels of N-acetyl-β-D-glucosaminidase (NAG) in non smoker elderly iron deficiency anaemia patients ≥ 65 years (4.97a±0.83 U/L) were significantly higher than in controls (2.17± 0.79 U/L) with higher mean values observed with increasing age (>70 years) (6.59a ±1.59 U/L). No statistically significant difference was observed between mean urinary NAG values in males (19 patients) (5.54 ± 1.43 U/L) and females (11 patients) (6.19 ± 1.57 U/L). In elderly iron deficiency anaemia patients of both age groups, urinary NAG values showed statistically significant negative correlation with haemoglobin levels (p=0.006 and <0.001 for patients ≥ 65 – 70 years and patients >70 years respectively) and were positively correlated with age (p<0.001 and <0.001 for patients ≥ 65 – 70 years and patients >70 years respectively). No correlation was detected between urinary NAG and haemoglobin values in either males or females (p=0.064 for males and p=0.821 for females).
The prevalence of anaemia in elderly patients ranges from 2.9% to 61% in men and from 3.3% to 41% in women. Higher rates of anaemia are found in hospitalized patients than in community dwellers, as well as in the oldest patients
Anaemia in elderly was defined as a haemoglobin concentration <13 g/dl for men and <12 g/dl for women. The same values suggested by the World Health Organization for younger adults
Anaemia in older persons reflects poor health and increased vulnerability to adverse outcomes
Urinary N-Acetyl-β-D-glucosaminidase (NAG) is a high molecular weight lysosomal enzyme that shows high activity in renal proximal tubular cells. It is usually not filtered in the glomerulus and its increased levels in urine reflect proximal tubular dysfunction of the kidney. NAG remains stable in urine and can be determined easily
The present study was undertaken to investigate urinary NAG as an index of renal tubular function in asymptomatic non smoker iron deficiency anaemia patients above 65 years of age and compare it with non anaemic persons of matched age and sex.
Materials and Methods
Two groups of asymptomatic non smoker elderly iron deficiency anaemia patients were studied. Group Ia consisted of 15 iron deficiency anaemia patients ≥ 65 – 70 years of age while group Ib consisted of 15 iron deficiency anaemia patients > 70 years. Nineteen patients were males and 11 were females. These patients were diagnosed during routine check up. History of reflux oesophagitis and / or peptic ulcer disease was obtained in the majority of these cases at a certain point of their life. Patients with known comorbid conditions and patients with creatinine clearance below 70 ml/min were excluded from the study. An equal number of age and sex matched subjects formed the control group (group II). Blood samples were analysed for complete blood count
Results and Discussion
Haemoglobin value was significantly lower in elderly anaemic patients of both age groups (10.74a ±0.99 g/dl) for those ≥ 65 years and 11.37 a±0.86 g/dl for those >70 years than controls (13.92 ± 0.92 g/dl) with non significant difference between groups Ia and Ib. Haemoglobin values in apparently healthy elderly people are generally lower than those in younger adults and differences between males and females in haemoglobin concentration that are seen in younger adults are lessened with aging as stated by
Mean urinary NAG levels were significantly higher in iron deficiency anaemia patients of both age groups. 4.97a±0.83 U/L for those ≥ 65 years and 6.59a ±1.59 U/L for those >70 years than controls (2.17± 0.79 U/L) (p<0.001) with significantly higher mean values observed in patients over 70 years than in those ≥ 65 – 70 years. The selection of NAG specifically as a marker of renal tubular dysfunction in this study was based on results of
No statistically significant difference was observed between iron deficiency anaemia males (19 patients) and females (11 patients) regarding urinary NAG values (p=0.46). No significant correlation was detected between urinary NAG and haemoglobin values in either males or females (p=0.064 for males and p=0.821 for females). Similarly, Moriguchi et al, 2003 demonstrated that urinary NAG was not affected in women with iron deficiency anaemia of sub-clinical degree.
The correlation between urinary NAG versus age and haemoglobin values in group Ia patients (≥65 – 70 years) and group Ib patients (>70 years) are represented by figures 1, 2 and figures 3, 4 respectively. There was a statistically significant negative correlation between urinary NAG and haemoglobin values (p=0.006 and <0.001 for groups Ia and Ib respectively) and a statistically significant positive correlation between urinary NAG and age (p<0.001 and <0.001 for groups Ia and Ib respectively) in elderly patients of both age groups. Ozçay et al, 2003 in a study done on children with iron deficiency anaemia showed that haemoglobin levels were significantly negatively correlated with urinary NAG/creatinine ratio. Also, there was significantly higher mean urinary NAG/creatinine ratio in patients than in controls denoting impaired renal tubular function even in children with iron deficiency anaemia.
In the current study, creatinine-corrected values were not used.
Correlation between urinary N-acetyl-β-D-glucosaminidase versus age and haemoglobin values in group Ia (≥65 - 70 years) (figures 1 and 2).
From the above results it can be concluded that in elderly patients, iron deficiency anaemia, even when asymptomatic, may be a contributing factor for the development of impaired renal tubular function. Thus, anaemia in the elderly should not be considered a normal consequence of aging; it should be early diagnosed and treated even if no clinical disease is immediately apparent.
The authors are thankful to Professor Mona Gamal, Professor of Microbiology & Immunology for her aid.