SummaryTo test the hypothesis that endurance performance may be related quantitatively to changes in blood, we measured selected blood variables then determined their reference ranges and associations with speed during an 80 km race. The plan had 46 horses in a 2 x 2 factorial design testing a potassium-free electrolyte mix and a vitamin supplement. (enabling then, perhaps, limiting). Stepwise regressions also included plasma urea concentration (limiting). The association of speed with less plasma acidity and urea suggests the potential for fat adaptation and protein restriction in endurance horses, as found previously in Arabians performing repeated sprints. Conditioning horses fed fat-fortified and protein-restricted diets may not only improve performance but also avoid grain-associated disorders.

Some of the clinical signs seen in horses during endurance races may result from increases in neuromuscular excitability and are related to plasma [K þ ] and [Ca þ þ ]. The present study aimed to test the following hypotheses:(1) Potassium supplementation will affect plasma [K þ ] and may result in clinical signs related to neuromuscular hyperexcitability during an 80 km endurance ride.(2) Plasma [Ca þ þ ] will reflect dietary cation-anion balance (DCAB) and calcium intake. Feeding with a high DCAB and high dietary calcium content (1.5% total calcium of daily ration) diets would lead to higher plasma [Ca þ þ ] during an endurance race than on feeding high DCAB diets with a moderate dietary calcium content (1% of total calcium of daily ration). The current study was undertaken during the 80 km endurance research ride in 2002 in Virginia, USA. Forty volunteer rider-horse pairs participated in the race. During the race, electrolyte mixtures with (EM þ K) and without (EM 2 K) potassium were supplied to 18 and 22 horses, respectively. After the race, the horses receiving EM 2 K during the race were supplied with a recovery formula containing potassium (EM-REC). The horses were fed in addition to their own forage (hay and pasture) either their own commercial concentrate (CC; 1% calcium, n ¼ 11) or one of two research-supplied concentrates during 3 months preceding the research ride, one concentrate rich in sugar and starch (SS; 2% calcium, n ¼ 15) and the other rich in fat and fibre (FF; 2% calcium, n ¼ 14). Peripheral blood samples were taken the day before, within 3 min of the arrival at the vet checks at 27, 48 and 80 km, and after 3 h of recovery. Plasma samples were analysed for pH, haematocrit (Hct), [Na þ ], [K þ ], [Cl 2 ], [Ca þ þ ], [Mg þ þ ], total protein (TP) and albumin [alb]. Effects of sampling times, treatments and interactions were evaluated by ANOVA in a mixed model with repeated measures and applied to the 25 horses that completed 80 km. Eliminated horses had their blood sampled before entering the elimination vet check and 3 h after elimination, and were compared with finishing horses by t-test. As the ride progressed, significant increases were found in plasma pH, [Na þ ], ½PO 2 4 , [TP], [alb], Hct and osmolality; and decreases in [K þ ], [Mg þ þ ], PCO 2 , [Ca þ þ ] and [Cl 2 ]. Horses supplied with potassium-free, sodium-rich electrolyte formulae (EM 2 K) had 12.5% lower (P ¼ 0.001) mean plasma [K þ ], 7.8% lower (P ¼ 0.024) TP and 8.4% lower (P ¼ 0.004) albumin at 80 km, and at 3 h after the race they had 6.8% lower (P ¼ 0.045) TP, when compared with EM þ K supplemented horses. Horses fed with SS and FF had higher [Ca þ þ ] at 27 (P ¼ 0.027), 56 (P ¼ 0.006) and 80 km (P ¼ 0.022) when compared with horses fed with CC. The lower [K þ ] in the EM 2 K group, and the higher [Ca þ þ ] in the SS-and FF-supplemented horses may help prevent increases in neuromuscular excitability and related clinical signs. The lower TP and albumin indicate less dehydration in the EM 2 K group and could help prevent re...

The utilization of folic acid during erythropoiesis is widely known and accepted in medical literature and deficiency is known to cause a characteristic megaloblastic anemia resulting from the inhibition or ineffective synthesis of DNA. Although the resultant megaloblastic anemia may take considerable time before evidence or symptoms present, there are more acute changes visualized on peripheral smear that are representative of a functional folate deficiency. In addition to erythrocyte macrocytosis, hypersegmentation of neutrophils can also be seen. Often times, despite these visualized changes measurement of serum folate and/or total red cell folate yields a result within the accepted “normal” range of the assay. It has been demonstrated that these visualized characteristics represent a functional folate deficiency and can be overcome with folic acid supplementation regardless of the measured folic acid levels indicating a yet to be understood mechanism of folate utilization. Here, we sought to measure the folic acid levels in the earliest erythrocyte progenitors in peripheral circulation, the reticulocytes. Methods Reticulocytes were isolated using anti-CD71 (the transferrin receptor) coated magnetic beads. After separation, a sample slide was made utilizing methylene blue for visual confirmation of reticulocyte isolation. The reticulocytes were then lysed with citric acid and a Nanodrop-1000 spectrophotometer was used to determine absorbance at 413 nanometers. This absorbance was used to determine the sample hemoglobin concentration from a simple calibration curve. The sample folic acid level was then determined using the lysing method utilizing mouse monoclonal anti-folate binding protein, paramagnetic particles coated in anti-mouse IgG, human serum albumin and milk folate binding protein. Results were calculated as nanogram of folate per gram of hemoglobin. Results Twenty-five samples from normal individuals, not taking folate supplements, were analyzed. The range of results was 2.51 to 17.38 with a mean level of 9.61. Conclusion This protocol effectively and efficiently allows for isolation of reticulocytes in numbers high enough for measurement of folate in nanogram per gram of hemoglobin. By this method we show the normal reticulocyte folate level to be approximately 3-15 ng/g of Hgb. This figure is consistent with the normal red cell folate concentration. Further analysis is planned for comparing these results in patients with a suspected functional folate deficiency but “normal” red cell folate levels. Efficient isolation of reticulocytes and measurement of folate levels will allow us to probe the underlying cause of acute folate deficiency seen in very sick patients. Disclosures: No relevant conflicts of interest to declare.

Objectives The laboratory received a request to report abnormal troponin (ab-TnI) as critical values (CVs) for ED patients. The laboratory information system (LIS) was programmed to identify only ED patients presenting with an ab-TnI. Only the first ab-TnI on presentation was critical. Unnecessary laboratory CV communications could impair overall turnaround time. Methods Mean troponin, ab-TnI test volumes, and ab-TnI from ED patients with suspected acute coronary syndrome were determined. The LIS team constructed a best practice alert in the Beaker module (EPIC, Verona, WI). The ab-TnI CV build filtered patients based on ab-TnI values and ED location. Based on pilot data, the build was adjusted to limit ab-TnI alerts to only the first ab-TnI result. The amended build logic was to trigger the alert if an ED location TnI was abnormal. At trigger, if the lowest TnI result in the last 24 hours is ≤0.040, the return “true.” If true, then no TnI >0.040 in the last 24 hours, call the ED because they currently have a result >0.040. If the answer is “false,” then do not call the ED. If the patient had no TnI in the last 24 hours, then the alert would be triggered as well. The system was piloted after education to the ED and laboratory teams. Results The mean TnI per day was 150; the mean ab-TnI was 63 (42%), of which 1.1 ab-TnI originated from the ED. After pilot go-live, the actual number of ab-TnI/day was 14.3. The alert logic was amended to limit the trigger to the first ab-TnI result, reducing the CV volume to 9.6/day. Conclusion The LIS can be leveraged to develop a clinically valuable and operationally manageable critical value alert system. Clinical and laboratory teams must be open to amending the process as needed to achieve success.