HYPONATREMIA
WORKSHOP
D6
STA. ANA – TANGCO
Dr. Monzon
Salient features
HISTORY
• 60 year old female
• cc: vomiting
• Fever, dysuria, frequency
• Headache, body malaise, nausea
• (-) epigastric pain, diarrhea
• (-) smoker and alcohol beverage drinker
• (+) HPN on telmisartan 40 mg and
hydrocholothiazide 12.5 mg
Salient features
PHYSICAL EXAMINATION
• wheel-chair-borne
• Orthostatic hypotension
LABORATORY FINDINGS
• Presence of infection
▫ Leukocytosis with predominance of neutrophils
▫ Slightly turbid urine
▫ Hyaline cast, Pyuria, Bacteruria
• Increased serum creatinine
• Decreased serum sodium = hyponatremia
GUIDE QUESTIONS
1. What is you diagnosis?
HYPOTONIC HYPONATREMIA
• a plasma Na+ concentration less than 135 mmol/ L
(patient: 123 mmol/L)
HYPONATREMIA
Pseudo-hyponatremia
N plasma
osmolality
↑ plasma
osmolality
Hypoosmolal hyponatremia
1° Na+ loss
1° water gain
1° water gain with
2° water gain
Hyperlipidemia
Hyperglycemia
Skin loss
Hypothyroidism
Heart failure
Hyperproteinuria
Mannitol
GI loss
AVP release
Hepatic
cirrhosis
Renal loss
SIADH
Nephrotic
syndrome
Chronic renal
insufficiency
1. What is the basis for your diagnosis?
▫
▫
▫
▫
▫
▫
▫
▫
Infection/ Fever
Vomiting
Nausea
Frequency
Serum Na = 123mmol/L
Orthostatic hypotension
Medications
Neurologic manifestations
Basis for diagnosis
• Vomiting
▫ Results in disturbances in acid-base balance,
dehydration and electrolyte depletion
▫ Na+ loss
• Infection
▫ fever  sweating  Na+ loss
• Frequency
▫ Na+ loss in urine
Basis for diagnosis
• Nausea
▫  ADH   H2O retention  hypoosmolarity
• Serum Na+ 123 mmol/L = Hyponatremia
• Orthostatic hypotension
▫ Sustained drop in systolic pressure (≥ 20 mmHg)
or diastolic pressure (≥ 10 mmHg) within 3
minutes of standing
▫ In nonneurogenic causes (i.e. hypovolemia) the
BP drop is accompanied by a compensatory
increase in HR (>15bpm)
Basis for diagnosis
• Medications
▫ Telmisartan - ARB
  angiotensin II   Na+ reabsorption in tubules
 Na + excretion  Na + loss
▫ Hydrochlorothiazide - Diuretic
 “diuretics-induced hyponatremia” is almost always
due to thiazide diuretics
  Na + reabsorption in tubules  Na + excretion 
Na+ loss
** Creatinine levels may increase when ACE inhibitors (ACEI) or
angiotensin-II receptor blockers (ARBs)
Basis for diagnosis
• Neurologic symptoms
▫ Related to osmotic water shift  increased ICF
volume (cerebral edema)
▫ Severity is dependent on rate of onset and
absolute decrease in plasma Na concentration
▫ As plasma concentration falls…
 Nausea, body malaise, headache, lethargy,
confusion and obtundation
▫ Plasma concentration < 120 mmol/L
 Stupor, seizures, coma
2. What other laboratory tests are needed
to be requested for the patient?
4 laboratory findings provide useful
information for the diagnosis of hyponatremia
▫
▫
▫
▫
Serum osmolality
Urine osmolality
Urine Na+ concentration
Urine K+ concentration
▫ Serum glucose & lipid profile*
Plasma Osmolality
High
Normal
Hyperglycemia
Hyperproteinemia
Mannitol
Hyperlipidemia
Low
Maximal volume of
maximally dilute urine
(<100mosmol/kg)
Bladder Irrigation
Yes
No
ECF Volume
Increased
Normal
Heart Failure
SIADH
Hepatic Cirrhosis
Exclude hypothyroidism
Nephrotic Syndrome
Exclude adrenal insufficiency
Renal Insufficiency
Primary polydipsia
Reset osmostat
Decreased
Urine Na Concentration
>20mmol/L
<10mmol/L
Extrarenal Na loss
Na wasting nephropathy
Remote diuretic use
Diuretic
Remote vomiting
Vomiting
Hypoaldosteronism
2. What other laboratory tests are needed
to be requested for the patient?
a. Serum osmolarity
▫ confirmation of true hypoosmolar hyponatremia
▫ determines fluid status to establish classification
of hyponatremia
 abnormally low in patients with hypoosmolar
hyponatremia
 normal or elevated in patients with hypertonic
hyponatremia due to serum hyperglycemia.
Serum osmolarity
Normal Range: 280 to 300mOsm/kg
Total osmolality (mOsm)
= 2 (Na + K) + Glucose(mg/dl)/18 + BUN(mg/dl)/2.8
= 2(123 + 3.7) + 98/18 + 20/2.8
= 2(126.7) + 5.44 + 7.14
= 265.98
 Hypotonic Hyponatremia
2. What other laboratory tests are needed
to be requested for the patient?
b. Urine osmolality
▫ may be helpful in establishing the diagnosis of
SIADH
▫ The appropriate renal response to hypoosmolality
is to excrete the maximum volume of dilute urine
▫ Patients with other forms of hyponatremia and
appropriately depressed levels of ADH have urine
osmolarities below 100 mOsm/L.
2. What other laboratory tests are needed
to be requested for the patient?
c. Urine Sodium Level
▫ to identify renal from nonrenal causes
 If due to nonrenal causes
 eg, vomiting, diarrhea, fistulas, GI drainage, third
spacing of fluids
 have avid renal absorption of tubular sodium and urine
sodium levels of less than 20 mEq/L
 If due to renal causes
 eg, diuretics, salt-losing nephropathy, aldosterone
deficiency
 have inappropriately elevated urine sodium levels in
excess of 20 mEq/L.
2. What other laboratory tests are needed
to be requested for the patient?
d. Urine Potassium Level
▫ Potassium levels often change with sodium levels
▫ ↓ Na+, ↑K+
2. What other laboratory tests are needed
to be requested for the patient?
• Serum glucose concentration
▫ Several physiologic states (e.g. hyperglycemia) exist
in which correct laboratory analysis yields low serum
sodium levels, but these levels do not reflect a true
hypoosmolar state.
▫ Accumulation of extracellular glucose induces a
shift of free water from the intracellular space to
the extracellular space
▫ Serum sodium concentration is diluted by a factor
of 1.6 mEq/L for each 100 mg/dL increase above
normal serum glucose concentration
3. How will you manage the patient’s
hyponatremia?
GOALS:
1. To raise the plasma Na+ concentration y restricting
water intake and promoting water loss
2. To correct underlying disorder
MANAGEMENT
• Check vital signs every 2 hrs
• Check for changes neurologic status – seizures
• Treat with Isotonic Saline (0.9 NaCl – 154 meq/L)
• Calculate sodium deficit
Calculation of sodium deficit:
Target Na: 125 – 135 mEq/L (average: 130 meq/L)
Na deficit = 0.6 x wt. in kg X (desired Na – actual Na)
= 0.6 x (50 kg) x (130 – 123)
= 210 mEq/L
Correction rate: <0.5 meq/L/hr
• First 8 hrs – 50% of calculated Na
• Next 16 hrs – other 50%
• Risk of development of Osmotic demyelination syndrome
in rapid correction of hyponatremia
3. How will you manage the patient’s
hyponatremia?
• Do not give hypertonic saline
 may result to overcorrection  Central Pontine
Myelinosis
• Do not give hypotonic fluids until serum Na
is > 125 mg/L
• Correct K+ deficit
RT, 60 y/o female
• CC: vomiting
• 1 week PTA --- fever
dysuria
frequency
self-medicated with Paracetamol
& unrecalled antibiotics
• 2 days PTA --- headache, body malaise,
nausea & vomiting
(-) epigastric pain, diarrhea
• ROS: unremarkable
• Personal History:
▫ non-smoker, non-alcoholic beverage drinker
• Past medical history:
▫ known hypertensive for 10 years
 Telmisartan 40 mg
 Hydrochlorothiazide 12.5 mg tablet OD
 discontinued amlodipine due to bipedal edema
• Family History:
▫ (+) hypertension – father & mother
▫ (-) Diabetes mellitus
▫ (-) Tuberculosis
Physical Exam
• Conscious, coherent, wheel-chair-borne
• Weight 50 kg
• Vital signs
▫ BP: 120/80 supine; 90/60 sitting
▫ CR: 90/min supine; 105/min sitting
▫ RR: 20/min
▫ T: 37o C
• Warm, dry skin, dry buccal mucosa, no active
dermatoses
Physical Exam
•
•
•
•
Pink, palpebral conjunctivae, anicteric sclera
Supple neck, JVP 3 cm at 30o angle
Symmetrical chest expansion, clear breath sounds
Adynamic precordium, AB 5th at LICS, MCL, no
murmurs
• Flabby abdomen, w/ normoactive bowel sounds,
soft, non-tender
• Extremities: (-) edema, pulses full and equal
• Neurological exam: normal
Drugs
Generic name
Paracetamol
Telmisartan
Hydrochlorothiazide
Amlodipine
Type of drug
NSAIDs
ARB
Diuretic
Indication
analgesic,
antipyretic
essential HPN
HPN
CCB
HPN & angina
Laboratory results: CBC
RESULTS
N.V.
Hemoglobin
0.132 g/dL
12 – 16 g/dL
↓
Hematocrit
0. 35
0.36 -0.46
↓
WBC
12.5 x 109/L 4.5 – 11 x 109/L
↑
Neutrophils
0.88
0.40 – 0.70
↑
Lymphocytes
0.12
0.22 – 0.44
↓
** Increased WBC with predominance of neutrophils
indicate presence of bacterial infection
Laboratory results
RESULTS
N.V.
FBS
98 mg/dL
< 100 mg/dL
N
BUN
20 mg/dL
10 – 20 mg/dL
N
Serum
creatinine
Serum Na
0.9 mg/dL
< 1.5 mg/dL
↑
123 mmol/L 136 – 145 mmol/L
↓
Serum K
3.7 mmol/L
N
3.5 - 5.0 mmol/L
Urinalysis
Result
Normal
Appearance
Yellow, slightly
turbid ♥
pH
6.0
Straw – dark
yellow,
clear – hazy
4.5 – 7.8
Specific
gravity
Albumin
1.020
1.003-1.029
(-)
(-)
Sugar
(-)
(-)
Urinalysis
Result
Normal
5/hpf ♥
0-2/lpf
Pus cells
10-15/hpf ♥
Up to 5/hpf
RBC
0-5/hpf
Epithelial cells
2-5/hpf, nondysmorphic
Few
Bacteria
Moderate ♥
(-)
Hyaline casts
Few
Slightly turbid urine
• Cloudy urine may not be pathologic
• Turbidity may be due to precipitation of crystals
or non-pathologic amorphous salts
• Materials that can cause turbidity:
▫ Phosphate
▫ RBCs
▫ Uric acid
▫ Ammonium urates
▫ Leukocytes
▫ Bacterial growth
▫ Mucus
▫ Blood clots
▫ Contamination
▫ Increased number of epithelial cells
♥
Hyaline Casts
• Can indicate mild to severe renal disease when
increased in numbers
▫ proteinuria of renal (eg., glomerular disease)
▫ extra-renal (eg., overflow proteinuria as in
myeloma) origin.
• Can be found in healthy individuals after heavy
exercise
♥
Pyuria
• Greater numbers of pus cells generally indicate
the presence of an inflammatory process
somewhere along the course of the urinary tract
▫ Acute infection of kidney (pyelonephritis)
▫ Cystitis (bladder)
▫ Urethritis (urethra)
• Pyuria often is caused by urinary tract infections,
and often significant bacteria can be seen on
sediment preps, indicating a need for bacterial
culture.
♥
Bacteruria
• Can be contamination from external sources
• Rapidly multiply in improper stored specimen
• With increased WBCs, indicative of urinary tract
infection
♥