Situation: A 19-year-old man is admitted with dark, cola-colored urine, puffy eyelids on waking, and a blood pressure of 158/98 mmHg. Three weeks ago he had infected sores on his legs that healed without treatment. His anti-deoxyribonuclease B (anti-DNase B) titer is high and his serum complement (C3) is low. Acute post-streptococcal glomerulonephritis (PSGN) is diagnosed. His urine output over the past 24 hours was 120 mL (7:00 AM–3:00 PM shift), 90 mL (3:00–11:00 PM shift), and 140 mL (11:00 PM–7:00 AM shift). The provider orders a 24-hour fluid allowance equal to the previous 24-hour urine output plus 500 mL for insensible losses, with half of the allowance given during the 7:00 AM–3:00 PM shift and the rest divided between the other two shifts. How much fluid may he take during the 7:00 AM–3:00 PM shift? Round off to the nearest whole number.

The 24-hour urine output is 120 + 90 + 140 = 350 mL. The 24-hour allowance is 350 + 500 = 850 mL. Half of it is given on the day shift: 850 ÷ 2 = 425 mL.

Core calculation
The previous 24-hour urine output is the sum of the three shift volumes: 120 mL + 90 mL + 140 mL = 350 mL. The provider orders a total daily fluid allowance of urine output plus 500 mL for insensible losses, so 350 mL + 500 mL = 850 mL per 24 hours. Half of that allowance is assigned to the 7:00 AM–3:00 PM shift: 850 mL ÷ 2 = 425 mL. The correct answer is 425 mL.

Why fluid restriction matters in PSGN
In acute post-streptococcal glomerulonephritis, glomerular inflammation reduces the filtration surface and traps sodium and water. The result is oliguria, edema, and hypertension—exactly the findings in this patient: puffy eyelids, dark urine, and a blood pressure of 158/98 mmHg. Fluid is restricted to match output plus insensible losses so that intravascular volume does not expand further and worsen hypertension or pulmonary edema. The insensible loss allowance of 500 mL accounts for water lost through skin and respiration, which cannot be measured directly.

How the shift distribution protects the patient
Giving half of the daily allowance on the day shift is a practical nursing strategy. The largest fluid portion is provided during waking hours when the patient is more likely to eat, take oral medications, and be monitored closely. The remaining 425 mL is divided between the evening and night shifts, which reduces the risk of excessive intake during sleep and allows for ongoing assessment of urine output and blood pressure before the next day’s allowance is recalculated.

Clinical monitoring tied to the calculation
This fluid prescription is not a one-time order. The nurse must measure each shift’s urine output accurately because tomorrow’s allowance depends on today’s total. Key point! If output improves, the allowance increases; if oliguria worsens, the allowance decreases. In PSGN, oliguria may persist for several days, so daily recalculation is essential. Watch out! Do not confuse the 500 mL insensible-loss add-on with the half-share calculation—the 500 mL is added first, then the total is split.

Pathophysiology link to assessment
The low serum C3 reflects complement activation by immune complexes deposited in the glomeruli, while the elevated anti-DNase B titer confirms a recent streptococcal infection. These findings support the diagnosis but do not change the fluid calculation. The fluid restriction targets the hemodynamic consequence of glomerular injury—sodium and water retention—rather than the immune process itself. Monitoring daily weight, lung sounds, edema, and blood pressure alongside strict intake and output is the core nursing responsibility in this setting.