Sjgren's syndrome presenting as hypokalemic periodic paralysis.

ARTHRITIS & RHEUMATISM Volume 36
Number 12, December 1993, pp 1735-1738
0 1993, American College of Rheurnatology
1735
SJOGREN’S SYNDROME PRESENTING AS
HYPOKALEMIC PERIODIC PARALYSIS
JAMES E. DOWD and PETER E. LIPSKY
We describe a 21-year-old Hispanic woman who
presented with hypokalemic paralysis as the initial
manifestation of Sjogren’s syndrome (SS). Our review
of the English literature revealed 12 previously reported
cases of SS and renal tubular acidosis (RTA). Paralysis
often preceded the sicca complex in those patients.
Renal function in the patients with hypokalemic paralysis was reduced compared with that in patients who had
primary SS and RTA but no history of hypokalemic
paralysis (P< 0.002). Hypokalemic periodic paralysis is
a rare manifestation of SS. It is seen more often in
patients with primary SS, may precede the classic sicca
complex, and may serve as a clinical marker for more
severe renal disease in patients who have primary SS
and RTA.
The periodic paralyses are a heterogeneous
group of disorders in which an acute onset of weakness is associated with abnormalities in serum potassium levels (1). Hyperkalemic periodic paralysis,
which may be associated with elevated or normal
serum potassium levels, has recently been linked to a
sodium-channel gene on chromosome 17 (2). Hypokalemic periodic paralysis and thyrotoxic periodic
paralysis are usually associated with a decrease in
total body and serum levels of potassium, respecFrom the Harold C. Simmons Arthritis Research Center,
University of Texas Southwestern Medical Center, Dallas.
Supported in part by an NIH Institutional Training Grant.
James E. Dowd, MD; Peter E. Lipsky, MD.
Address reprint requests to James E. Dowd, MD, Harold C.
Simmons Arthritis Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX
75235-8844.
Submitted for publication March 15, 1993; accepted in
revised form June 8, 1993.
tively. Genetic linkages have yet to be defined, but
dominant inheritance is common. Hypokalemic periodic paralysis has also been described in patients with
potassium-wasting renal tubular acidosis (RTA) (3).
We report here a case of hypokalemic periodic paralysis as the presenting symptom of primary Sjogren’s
syndrome (SS).
CASE REPORT
A 21-year-old Latin American woman residing
in the United States, presented in March 1992 with a
2-day history of progressive weakness and myalgias
that began in her lower extremities. Twenty-four hours
before admission, the patient developed nausea, vomiting, and quadriparesis.
A similar episode had occurred 1 month previously, and she was evaluated locally. Laboratory
values at that time were K 2.3 mEq/liter, Na 133
mEqAiter, C1 104 mEq/liter, C 0 2 18 mEq/liter, hemoglobin 9.8 g d d l , and hematocrit 24.0%, and normal
thyroid function. The patient traveled to Mexico for
therapy, and was given 2 anthelmintics, an anxiolytic,
multivitamins with iron, and oral potassium. The
weakness improved with these medications and with
oral hydration. She had no other episodes of weakness
until the current illness.
The patient had no history of fever, chills, rash,
abdominal pain, diarrhea, tenesmus, dysuria, polyuria, laxative or diuretic use, pica, or toluene ingestion. Review of systems revealed periodic painless
swelling of the angle of her jaw over the previous 3
years, most recently, 8 months prior to admission.
These episodes were accompanied by dry mouth and
thirst, but no dryness of the eyes.
1736
Examination on admission to the hospital revealed a thin and alert woman of normal body habitus,
with a recumbent blood pressure and pulse of 100/65
mm Hg and 76 beats per minute and assisted sitting
blood pressure and pulse of 88/palpable and 85, respectively. Her temperature was 36.8"C orally and
respiratory rate was 18 per minute. Her sclera were
anicteric, and conjunctiva noninjected. Fundi were
normal.
She had a bulging, nonerythematous left tympanic membrane. There was firm, nontender swelling
over both parotids. Her oropharynx was dry, with
glossitis. There was no cervical, axillary , or inguinal
lymphadenopathy. Her thyroid was normal. Her chest
was clear. There was a II/VI systolic ejection murmur
at the left lower sternal border, without radiation. Her
abdomen was soft and nontender, without hepatosplenomegaly or costovertebral angle tenderness. Her
skin was dry, but otherwise normal. There was no
joint or soft tissue swelling, tenderness, or deformity.
Neurologic examination revealed grade 3/5
weakness of the proximal muscles and grade 4/5
weakness distally. She was unable to stand or walk.
Examination of the cranial nerves, reflexes, and sensory status gave normal results.
Laboratory examination revealed the following
values: Na 136 mEqfliter (normal 137-145), C1 110
mEqfliter (normal 101-1 1 l), K 1.6 mEqfliter (normal
3.6-5.0),HCO, 9 mEqfliter (normal 22-31), anion gap
+7 (normal <12), blood urea nitrogen 12 mgidl (normal 7-21), serum creatinine 1.1 mg/dl (normal 0.7-1.5),
Mg 2.2 mEq/liter (normal 1.4-1.8), Ca 9.2 mgidl (normal 9.1-10.6),PO4 2.6 mg/dl (normal 2.5-4.5),creatine
kinase 88 unitdliter (normal 35-230), and total protein
10.1 gmldl (normal 6.3-8.2).The serum white blood
cell (WBC) count was 18,300/mm3, the hemoglobin
level was 10.6 gm/dl (normal 12.0-15.2), the platelet
count was 214,000/mm3(normal 140,000-450,000), and
the erythrocyte sedimentation rate was 74 mmhour
(normal 0-15). Analysis of blood gases showed the
following levels: pH 7.36 (normal 7.34-7.44), Pco, 30
mm Hg (normal 35-45), Po, 108 mm Hg (normal
75-loo), and HCO, 17 mEq/liter (normal 22-26). Urinalysis showed a pH value of 7.0,specific gravity of
1.010,a trace of protein, 3-5 WBC per high power
field, Na value of 38 mEq/liter, K of 15 mEq/liter, CI of
39 mEqAiter, urinary anion gap of +14, and urinary
osmolality of 133 (normal 301-896).
An initial diagnosis of hypokalemic periodic
paralysis with a non-anion gap acidosis was made. The
patient was begun on volume replacement and a
DOWD AND LIPSKY
regimen of combination oral and intravenous potassium. The presence of a positive urinary anion gap and
a high urinary pH despite hyperchloremic acidosis was
consistent with distal renal tubular acidosis. Subsequently, oral citrate solution was administered to
compensate for the renal tubular acidification defect.
The patient began to regain her strength within 24
hours of initiation of therapy. Approximately 1,500
mEq of supplemental potassium was administered in
the first 3 days of hospitalization.
The history of dry mouth and periodic parotid
swelling confirmed by examination suggested SS as
the etiology of the RTA. A Schirmer's test on hospital
day 2 demonstrated 2 mm of tear flow at 5 minutes
(normal 215 mm). Biopsy of the minor salivary glands
of the lip showed >2 foci of lymphocytes/4 mm2
(Greenspan scale), indicative of Sjogren's syndrome.
Antinuclear antibodies were present at a titer of 1540,
in a speckled pattern, rheumatoid factor was 497 IU/ml
by nephelometry (normal <30), and anti-Ro/SS-A
antibodies were present, confirming the pathologic
diagnosis. The elevated total protein level was further
evaluated by serum protein electrophoresis, which
revealed a polyclonal gammopathy. The ferritin (10
ngiml) and serum iron (26 pg/dl) levels were consistent
with iron deficiency anemia.
By hospital day 3, the patient was able to walk
without assistance, and her muscle strength was normal. The discharge diagnoses were SS and distal RTA
causing hypokalemic periodic paralysis. At 4 months
of followup, the patient reported dry mouth, but had
no symptoms of dryness of the eyes or further weakness. Laboratory values at that time were sodium 139
mEq/liter, potassium 3.5mEq/liter, chloride 102 mEq/
liter, bicarbonate 23 mEq/liter, and creatinine 1.O
mg/dl. Oral potassium and citrate were continued.
DISCUSSION
This case represents 1 of only 3 cases reported
from the United States and 10 other cases in the
English literature. Although our patient was Spanish
speaking and born in Mexico, her name is Germanic,
suggesting other European genetic influences. This
differs from the Asian bias suggested by the country of
origin in 9 of the other 12 reported cases (Table 1). A
similar Asian bias has been reported in patients with
thyrotoxic hypokalemic periodic paralysis (1).Tissue
typing of these patients (Table 1) was not available for
comparison.
Our patient met all 4 of the proposed criteria for
PRIMARY SS AND HYPOKALEMIC PERIODIC PARALYSIS
1737
Table 1. Hypokalemic periodic paralysis as the predominant manifestation of Sjogren’s syndrome*
Case number
Agelsex
Race
Other signs and
symptoms
Potassium(mEq1liter)
Urine
PH
Protein
Creatinine clearance
(mllminute)
ESR
Polyclonal
gammopathy
Diagnostic
Sch./Sial.
Anti-Rolanti-La
RFIANA
Biopsy
Reference
Index case
1
2
21lF
LAm
Sicca
3QlF
Jpn
-
38lF
Fr
RA, HB
1.6
1.5
1.4
1.2
1.7
2.4
1.0
7.0
trace
NA
7.5
NA
68
7.5
3+
52
NA
NA
NA
NA
NA
NA
NA
NA
NA
7.5
74
NA
NA
73
48
88
NA
+ N A
+/NA
+I+I+
Lip
-I+
+/NA
+
-
+
3
4
5
34lF 32lF 36lF
Ch
Ch
Ch
-
+
6
63lF
Swed
Sicca
7
6.5
2+
NA
NA
NA
+
7.5
-
NA
NA
NA
+/NANA/+ NA/+ +I+ +/NA +/NA
+I+ +I+ +I+ -I-,ENA NA
NA
+I+ NA +I+
+I+
+/+
NA
Lip Lip, renal Lip Renal Lip
NA Renal Lip
11
12
13
13
13
14
8
15
+I-I+I+ +I-,ACA
9
10
11
12
34lF 30lF
14lF
41lF
54lF
36lF
Fil
NA
JPn
Jpn
Jpn
Jpn
NC Sclero- Leg pain,
RP,
RP Arthral.
derma growth retard. arthral.
2.3
2.8
2.5
2.3
2.6
2.1
1+
NA
+
8
7.0
1 +/AA
70
7.0
1+
62
6.9
I+
54
6.6
1+
38
27
49
32
10
-
-/NA
NA
+/+
Lac., par.
7
+/NA
NA
+I+
Lac., par.
7
+
+
+
+/NA +/NA
NA
NA
+I-IRenal Lac., par.
7
7
* LAm = Latin American; Jpn = Japanese; Fr = French; Ch = southern Chinese; Swed = Swedish; Fil = Filipino; NA = not available;
RA = respiratory arrest; HB = heart block; NC = nephrocalcinosis; growth retard. = growth retardation; RP = Raynaud’s phenomenon;
arthral. = arthralgias; AA = amino acids; ESR = erythrocyte sedimentation rate; Sch.lSia1. = Schirmer’s testkadionuclide sialography; ENA
= extractable nuclear antigen: RFIANA = rheumatoid factorlantinuclear antibody; ACA = anticentromere antibody; Lac. = lacrimal gland;
par. = parotid gland.
the diagnosis of SS (4). Moreover, her young age, sex,
early extraglandular involvement in the form of RTA,
and the presence of ROBS-A antibodies were consistent with the primary SS phenotype (5). Hypokalemic
periodic paralysis was the presenting manifestation of
primary SS in this patient, preceding symptoms of
xerostomia and xerophthalmia. Review of the other
reported cases appeared to corroborate this observation, with quadriparesis preceding arthrlagias, Raynaud’s phenomenon, sicca symptoms, and symptomatic urinary calcinosis. In cases 6, 8, 9, and 12 the
“other symptoms” preceded or accompanied quadriparesis. Compared with the patients studied by Pavlidas, Siamopolous, and colleagues (5,6), this subset of
patients with primary SS (Table I) appeared to seek
medical attention earlier in the course of disease and at
a younger average age (36 versus 52 and 50 years,
respectively).
Renal involvement (symptomatic and asymptomatic) has been estimated to occur in 3040% of SS
patients (6). SS patients may have clinical and pathologic evidence of both proximal and distal types of
RTA (7,8). Our patient exhibited no evidence of proximal RTA, but only distal abnormalities that may have
related to her marked hypergammaglobulinemia. The
clinical severity of RTA in this group (Table 1) may be
a reflection of more extensive renal pathology, as
suggested by their lower average creatinine clearance
rate than in patients with primary SS and RTA, but
without hypokalemic paralysis (57
12 muminute
versus 83 2 9 ml/minute; P < 0.002) (6). It should be
emphasized that our patient had a normal serum
creatinine value when she first presented and has not
exhibited renal failure over the ensuing 2 years of
followup. Therefore, renal failure, as opposed to tubular dysfunction, may not be a part of this syndrome.
Renal biopsies in these patients (Table 1) usually
showed evidence of interstitial nephritis, with lymphocytic and plasma cell infiltration and tubular atrophy.
Similar pathology has been described in patients with
SS and renal tubular acidosis without hypokalemic
periodic paralysis (5).
Our patient’s history of only 1 previous episode
of paresis, the lack of intercurrent or chronic weakness, the normal serum creatine kinase value, and her
rapid response to therapy with full recovery of
strength precluded the need for electromyography
andlor muscle biopsy for diagnosis. Some patients
with SS may develop an inflammatory myopathy resembling polymyositis or dermatomyositis; moreover,
*
1738
a noninflammatory myopathy with pathologic changes
consisting of microcysts, resembling large lipocytes
within the muscle fascicles, has been described in SS
(9). It is unlikely that our patient had a primary
myopathic process, although chronic or recurrent hypokalemia may lead to vacuolar degeneration of myofibrils (1).
The use of the urinary anion gap (Na + K - C1)
as a measure of urinary ammonium excretion during
acidosis may obviate the need to perform acid load or
bicarbonate excretion tests to confirm RTA (10). In
our patient, the urinary anion gap was utilized on
admission to determine the cause of hyperchloremic
metabolic acidosis. Our patient had a positive urinary
anion gap in the presence of acidemia, which suggested an inability to excrete excess acid, a feature
consistent with distal RTA. A negative urinary anion
gap in the presence of hyperchloremic acidosis may be
normal or may suggest a gastrointestinal loss of potassium such as occurs with diarrhea. The presence of
hypokalemia and an inappropriately high urine pH, as
in our patient, or urinary calcinosis may further confirm the diagnosis of distal RTA.
As this case and others like it demonstrate,
hypokalemic periodic paralysis as the initial manifestation of primary SS is rare, but when it occurs, it may
precede symptoms of xerostomia and xerophthalmia.
This presentation may also serve as a clinical marker
of more severe renal disease in patients with primary
SS and RTA. The diagnosis of primary SS should be
considered in premenopausal women, especially those
of Asian origin, but in other racial groups as well, who
present with rapidly progressive weakness and hypokalemia, with or without the sicca complex. Calculation of the urinary anion gap may be utilized during an
acute episode of hyperchloremic metabolic acidosis to
quickly confirm the diagnosis of distal RTA. Acute
therapy with potassium and alkali replacement must
DOWD AND LIPSKY
be tailored to the individual patient based on serum
chemistries. Long-term followup should monitor electrolytes and renal function as well as clinical disease.
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