The upholstery of a dialysis chair is either fibre or foam filled. In this case, it was made from low-density polyurethane foam. There are few case reports on polyurethane foam ingestion in non-renal patients. The presenting features include abdominal pain, constipation, as in our patient, and intestinal obstruction from bezoar formation. There are no reported cases in renal patients or an association with fluid retention.
The reported causes of pica in renal patients are clay, dirt, aspirin, flour, baking soda and ice.1
The underlying aetiology is unknown but various theories have been postulated. The most popular of which is related nutritional deficiency (particularly iron and zinc deficiency). The other theories suggest psychosocial, cultural influences or sensory gratification associated with ingesting these non-food materials (ie, taste, texture, smell) as an underlying cause.2
We could find no clinical or biochemical evidence (see Investigations) to suggest nutritional deficiency in our patient. There were no acute psychosocial triggers for her behaviour and no other reported form of pica. It is likely that having learning difficulties played a role.
Irrespective of the aetiology, the consequences can be severe. These complications vary from direct toxic effects, malnutrition and metabolic derangement to obstructive gastrointestinal symptoms. Large interdialytic weight gain has been noted to occur in haemodialysis patients with pica but a causal relationship has not been conclusively established.1 3 4
In a prospective study by Ward and Kutner1
looking at haemodialysis patients with pica, those of concern were more likely to be young female patients of African-American origin. The substances involved included starch, dirt and aspirin with two-thirds of cases involving ice ingestion. Fifty-eight per cent of these patients reported excessive interdialytic weight gain. Interestingly, the mean interdialytic weight gain was smaller in patients with ice pica compared to the others.
In contrast, a small case-control study by Obialo et al
, which looked at clay pica in haemodialysis patients,5
showed no statistically significant difference in interdialytic weight gain between case and control.
While the debate lingers as to the exact relationship between pica and fluid gains, this case would suggest that it is worth looking carefully for it in such patients.
- Pica can occur in haemodialysis patients.
- Reported offending substances include ice, baking soda, aspirin, clay and now polyurethane foam.
- Renal patients with pica have reported excessive interdialytic weight gain.
- There is a case for assessing patients with excessive fluid gain for pica.