# *** Hyponatremia [symptomatic; acute vs. chronic >48 hours; mild 130-134, moderate 120-129, severe

# *** Hyponatremia [symptomatic; acute vs. chronic >48 hours; mild 130-134, moderate 120-129, severe <120]
Checklist
-- ABCs: if severe (<120) or symptomatic, page renal and consider ICU due to need for close monitoring and frequent lab draws
‍-- Chart Check: baseline Na, medication use
-- Admission Criteria: *** no strict criteria
-- HPI Intake: diet, alcohol, meds, co-morbidities including CHF, cirrhosis, ESRD, cancer
-- Can't Miss: *** EtOH use, seizure risk, rapid overcorrection
-- Admission Orders: *** serum Osm, Urine Osm, Urine Na, strict I/O's, BNP if evidence of CHF; fluids vs diuretics
-- Initial Treatment to Consider: if severe with symptoms - immediate hypertonic (3%) saline 100mL bolus over 10 mins to get Na up 4-6 points

Assessment:
-- History: *** meds, diet, EtoH use, hx of CHF, cirrhosis, CKD, cancer, endocrine disorder
-- Clinical: *** seizure, N/V, weakness
-- Exam: *** AMS, weakness, volume exam
-- Data: *** Na, Serum Osm, Urine Osm, Urine Na (SOsm <300 if hypotonic, UOsm >100 if ADH present, UNa <30 if RAAS active)
-- Etiology/DDx: *** hypovolemia, decreased effective circulating volume (3rd spacing), SIADH (infection, malignancy, meds, primary brain injury or lesion), ESRD, primary polydipsia, low solute

Working Through The Differential:
Is this hypotonic hyponatremia? (SOsm <300) - if not, "pseudohyponatremia" from hyperglycemia, protein
Is ADH present? (UOsm > 100) - if not, primary psychogenic polydipsia, tea and toast, beer potomania
Is RAAS On? (UNa <30) - if yes, hypovolemia or 3rd spacing 2/2 CHF or cirrhosis; if no, salt wasting via SIADH, diuretic use, ESRD, or endocrine etiology
‍
The patient's HPI is notable for ***. Exam showed ***. Labwork and data were notable for ***. Taken together, the patient's presentation is most concerning for ***, with a differential including ***.

Plan:
Workup
-- Serum Osm, Urine Osm, Urine Na
-- if unclear etiology, can also send TSH, lipid screen, SPEP/UPEP, serum cortisol and ACTH, UDS, BNP
-- BMP q ***

Treatment
-- Correction Goal: *** at a rate of 4-6 per 24 hours
-- Volume: *** (IVF vs diuresis) Severe with Sxs - 3% NaCl 100mL bolus over 10 min (to Na raise 1-3) given up to 3x to get Na up 4-6; Severe without Sxs - 3% Na Cl drip until Na >125; Otherwise, volume repletion by exam
-- if ADH Absent - restrict fluids, slow introduction of solute; high risk of overcorrection
-- if ADH on, RAAS Active - replete if hypovolemic, diuresis if CHF, nephrotic syndrome
-- if ADH on, RAAS Off - likely SIADH, restrict 0.8L/day, salt tabs 1g TID; consider Lasix, vaptans