Evidence suggests that nutritional status may be maintained with lower protein intakes than previously recommended. However, the evidence base is limited and further randomised controlled trials are required to establish the optimal protein intake for dialysis patients.
SUMMARYSickle trait is the commonest of the sickle haemoglo binopathies and affects approximately 9% of the Afro-Caribbean population of North America. ] Traditionally the condition was considered to be benign, important only for its genetic implications, 2 , 3 but some authors have challenged this viewpoint. Spontaneous vitreous haemorrhage, 3 , 4 proliferative retinopathr and other ocular lesions have been described, albeit in the presence of some precipitat ing factor.Factors known to enhance sickling of red blood cells, thereby increasing the risk of vascular throm bosis, include hypoxia, dehydration, acidosis, hyper viscosity and the percentage of abnormal haemoglobin.6 The combination of sickle trait and a significant degree of one or more of these factors may provoke sickle retinopathy. Three cases are reported to emphasise the importance of considering sickle trait as relevant to the management of eye disease in at-risk patients. presented to the eye casualty having been hit in the left eye by a paper pellet. On examination the vision was right 6/5 and left 6/18. On the left side a 5 mm hyphaema was present, the pupil was round and reactive and the intraocular pressure (lOP) was 18 mmHg. Dilated funduscopy was normal. The follow ing day the hyphaema had reduced in size but the lOP had risen to 38 mmHg, hence topical and oral ocular antihypertensive agents were introduced. Haemoglobin (Hb) electrophoresis revealed AS sickle trait with an HbS concentration of 38.3%. The next day the lOP had risen to 53 mmHg and oral glycerol was added to the regime. There was good response to this treatment, with the lOP returning to normal and gradual resolution of the hyphaema. Gonioscopy confirmed angle recession nasally.Six days after admission the patient was noted to have scattered preretinal and sub hyaloid haemor rhages in the temporal mid-periphery, but no retinal tears were identified. After 14 days the visual acuity was 6/6-3, the eye was quiet with no hyphaema and the rop was 13 mmHg. The haemorrhages in the mid-periphery remained and occluded vessels invol ving almost all of the peripheral retina were seen (Fig. 1). Six weeks after the incident the haemor rhages had resolved but there was no change in the appearance of the peripheral vasculature. A fluor escein angiogram (Fig. 2) showed extensive periph eral occlusion but no neovascularisation.The other fundus is normal and the lOP has remained at 12-15 mmHg on no treatment.
Case 2A 59-year-old Jamaican woman was referred from the diabetic clinic because of reduced visual acuity and the finding of background diabetic retinopathy. She had been an insulin-dependent diabetic for 30 years, hypertension had been diagnosed 4 years previously and this was well controlled on nifedipine and a diuretic. She did not smoke. Visual acuity was Eye (1995) 9,589-593
London
SUMMARYRetinopathy associated with sickle-C and sickle cell disease is well described. Sickle trait and haemoglobin C trait are generally considered benign conditions, with infrequent systemic manifestations. Rare cases of retinopathy in sickle trait, in the presence of contrib utory factors, exist and we recently reported three such patients. The occurrence of retinopathy in haemoglobin C trait is even less well documented. Haemoglobin C does not cause red blood cell sickling but is known to decrease erythrocyte plasticity and increase blood viscosity. We report three cases in which haemoglobin C trait was associated with significant peripheral vascular occlusion and seafan formation (confirmed by fluorescein angiography) similar to that seen in sickle retinopathy. Two patients had coexistent sys temic disease (hypertension and diabetes mellitus).Vitreous haemorrhage was the presenting feature in two patients. It is evident that haemoglobin C trait may be associated with sight-threatening complications. The haemorrhage resolved to reveal non-perfusion of the retina anterior to the temporal equator with
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